Iran shut down a British power plant for four days in an unprecedented cyber attack, The Telegraph has revealed. It is thought to be the first time that hackers affiliated to the Iranian regime have succeeded in closing down such a facility in the UK, and is believed to be the most successful cyber attack of its kind.

The Telegraph understands that the incident took place at the same time as a series of attacks on US water infrastructure last month, which affected 12 states and caused concern in the White House. British officials refused to be drawn on which power plant had been affected, citing security concerns, but it is understood that the facility was disabled for four days while staff fought to bring it back online.

It is understood that the plant affected was relatively small and that the outage had no impact on the UK’s wider power supply or energy generation. In response, the UK government briefed the chief executives of power companies and wrote to businesses with advice, direction and next steps.

The incident is understood to have been reported to the country’s National Cyber Security Centre (NCSC), a public-facing branch of the GCHQ spy agency that issues advice to companies on keeping national infrastructure safe from foreign threats. British and American intelligence agencies have repeatedly warned of the risk posed by hackers from Russia, China, Iran and North Korea, which bombard critical national infrastructure and government agencies with attacks on a daily basis.

Major incidents have previously brought down NHS systems, schools and commercial manufacturing facilities, including production lines at Jaguar Land Rover. Foreign hacking groups have also stolen customer information from retail businesses, including attacks last year, and voter records from the UK Electoral Commission.

However, no hacker is thought to have ever succeeded in bringing a British power plant to a standstill, despite warnings that attacks on national infrastructure are commonplace. It is unlikely that the attack against the UK power plant was intended to inflict genuine harm on civilians, and is not thought to have been widely noticed by the public.

But it is possible that the incident was designed to prove that hackers linked to Iran’s Islamic Revolutionary Guard Corps could gain access to systems in the UK and close down sensitive infrastructure sites. There are dozens of small-scale power plants across Britain connected to the grid.

Many of them are gas-fired and only used for a few hours a week, for example when wind speeds are low and extra energy is needed. A four-day outage at such a facility would not affect the wider grid. Some factories and other facilities such as hospitals also have their own separate power generators.

The US hacks affected dozens of wastewater treatment plants, causing flooding and a loss of pressure from taps, and forcing some authorities to advise customers to boil their water before drinking it. The first reports of an incident emerged in Minnesota on July 26, followed by a series of similar security breaches in Michigan, Georgia, South Dakota and New Jersey.

The FBI attributed the incidents to “malicious cyber actors”, but US government sources later confirmed to media outlets that the threat was likely to have originated in Tehran. Iran has stepped up its cyber attacks on Western countries in the wake of the conflict in the Middle East, and especially since the US and Israel began airstrikes in February.

Suspected Iranian attacks have been reported in Germany, Poland, Finland, Belgium and Albania, although Israel and other Middle Eastern countries are the most common targets. In March, the NCSC advised British organisations to review their security approaches in light of the conflict, while Richard Horne, the agency’s chief executive, said in June that it had dealt with more than 200 attacks on critical national infrastructure in the previous year.

The NCSC does not routinely acknowledge individual incidents, and declined to comment on the attack on a UK power plant. Experts have long warned that the UK is unprepared for the scale of the threat of malicious cyber attacks from foreign adversaries, and the intelligence and security committee, which oversees spying agencies, reported last year that the chance of an Iranian cyber attack on British infrastructure was “unlikely”.

However, the committee also said that cyber warfare was a “significant area of asymmetric strength” for Iran, which spends tens of millions of dollars on hacking groups, each containing hundreds of people. An official risk assessment by the UK Cabinet Office, published last month, found the risk of a serious and successful cyber attack against domestic infrastructure was between 5pc and 25pc, but warned that “AI can automate the process of launching cyber attacks, making them faster, more efficient and lower the barrier for entry”.

A UK government source said: “We have thresholds for important generators to legally notify us of cyber activity, and this site is nowhere near. It’s a very small-scale site, less than a rounding error compared to grid capacity. “The UK has a highly resilient energy system.

We work closely with the energy sector to protect infrastructure and ensure the highest security standards. “This story refers to an incident impacting a small-scale energy generator, and at no point was there a risk to the wider energy system.

A cyber attack shut down a small power facility in the UK last month following warnings about a pattern of disruptive activity by state and non-state actors. Hackers affiliated to the Iranian regime were behind the attack - which lasted four days, the Telegraph reported.

The newspaper added that the incident coincided with a series of attacks on US water infrastructure in July. The UK government said that a "small-scale energy generator" was affected and that the wider energy system had not been put at risk, but did not disclose which site was affected.

The Department for Energy Security and Net Zero briefed energy chiefs and wrote to companies with advice in response to the attack. A government spokesperson said: "The UK has a highly resilient energy system. We work closely with the energy sector to protect infrastructure and ensure the highest security standards.

"This story refers to an incident impacting a small-scale energy generator, and at no point was there a risk to the wider energy system." The incident was reported to the National Cyber Security Centre (NCSC), an arm of GCHQ, The Telegraph reported.

It is understood that the NCSC did not receive any reports of outages in relation to the cyberattack. The centre has previously warned about a pattern of disruptive cyber activity targeting UK organisations by state and non-state actors. NCSC chief Richard Horne warned earlier this year that hostile states including Iran were increasingly targeting the UK's infrastructure with online attacks.

Liberal Democrats foreign affairs spokesperson Calum Miller said: "Reports that Iran-linked hackers shut down a UK power plant show the threat posed by hostile foreign powers to our national security. "The Government must urgently strengthen plans to secure our energy infrastructure and protect us from attack.

Cyber attack shut down UK power plant – Telegraph A small-scale British power plant was taken offline because of a cyber attack, with UK authorities blaming an Iranian-linked hacking group, The Telegraph reported on Saturday. In the UK, dozens of small-scale power plants are connected to the national grid, many of them gas-fired facilities that operate for just a few hours a week.

The newspaper did not specify which facility was targeted but noted that it was out of operation for four days in July. The authorities reportedly notified the National Cyber Security Centre, a public-facing branch of the Government Communications Headquarters, held emergency briefings for energy company executives and sent businesses guidance on strengthening security measures.

According to The Telegraph, the incident coincided with a series of cyberattacks targeting water infrastructure in the US that affected facilities in 12 states. Earlier this month, CBS News cited sources as saying that more than 30 community water systems had been impacted and that the attacks might be linked to Iran-backed hackers.

Some utilities reportedly lost critical remote-control capabilities, forcing operators to switch to manual mode. In several cases, the hackers gained remote access to pumps, valves, and water pressure. Western intelligence agencies have repeatedly claimed that critical national infrastructure and government bodies face a constant threat from hackers in Iran, North Korea, China, and Russia – allegations that the authorities in each country have dismissed.

Moscow says that the West habitually cites the supposed threat of external aggression to justify a massive military buildup and the development of offensive cyber capabilities.

Iranian cyber attack shuts down UK power plant for four days, report says Iranian hackers shut down a British power plant for four days in an unprecedented cyber attack, the Sunday Telegraph reported. According to the newspaper, the incident appears to mark the first time Iran-linked hackers have successfully shut down such a British facility.

The incident occurred alongside a series of attacks on US water infrastructure last month, which affected at least 12 states and caused concern in the White House. The Telegraph said that British officials have refused to disclose which facility was affected, citing security concerns.

A spokesperson for the Department for Energy Security and Net Zero said that the attack impacted a "small-scale energy generator", posing no "risk to the wider energy system". New MEE newsletter: Jerusalem Dispatch Sign up to get the latest insights and analysis on Israel-Palestine, alongside Turkey Unpacked and other MEE newsletters No outages were reported following the incident, according to the National Cyber Security Centre (NCSC), which deals with attacks on critical infrastructure.

The British government subsequently briefed chief executives of power companies and wrote to businesses with advice, direction and next steps. Escalation The attack appears to mark an escalation following the UK's decision to grant the US permission to launch "defensive operations" against Iran from British bases.

In March, Prime Minister Keir Starmer’s government had granted permission to the US military to use the Royal Air Force base in Fairford and the joint facility on Diego Garcia, for limited operations against Iranian missile facilities that "directly threatened British personnel", regional allies, or sovereign assets.

The authorisation was subsequently expanded, allowing the US to launch strikes against active Iranian missile infrastructure targeting commercial oil shipping channels in the Strait of Hormuz. In June, an Iran-linked hacker-activist group, Handala, claimed responsibility for a cyber intrusion targeting water facilities in California, saying the action was carried out in retaliation for alleged US strikes on water infrastructure in southern Iran.

The group said it had obtained data from the systems and described the breach as a warning to Washington. In a statement, Handala said it had the capability to disrupt water supplies but "stopped short of actually cutting off water to American cities", citing a different ethical code than its adversaries.

The group also said it had published five gigabytes of data as evidence of the intrusion. In April, the group said it obtained at least 19,000 sensitive files after targeting the personal phone of former Israeli army chief of staff, Herzi Halevi. "All your top-secret facilities, crisis rooms, maps, and even the tiniest details of your command centres have long been like an open book to us," the group said in a statement posted on its website.

The files, some of which were seen by Middle East Eye, showed Halevi meeting with Arab officials. In one undated photo taken in Qatar, Halevi could be seen attending a meeting with former US Central Command (Centcom) chief Michael Kurilla. Middle East Eye delivers independent and unrivalled coverage and analysis of the Middle East, North Africa and beyond.

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