Hackers linked to Iran have been blamed for a cyber-attack that caused a British power plant to be temporarily shut down.

The incident involved a small-scale energy generator, according to the UK government and at no point was there there risk to the wider energy system.

However, it marks an apparent escalation in the threat posed by Iran after the UK said it had given permission for the US to launch “defensive” operations against Tehran from British bases.

The power plant was shut down for four days as a result of the attack last month, according to the Sunday Telegraph, which first reported it.

A spokesperson for the Department for Energy Security and Net Zero said: “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 UK has a highly resilient energy system. We work closely with the energy sector to protect infrastructure and ensure the highest security standards.”

The National Cyber Security Centre (NCSC), which deals with attacks on critical infrastructure, is understood not to have received any reported outages from regulated operators of power stations.

Hostile states such as Russia, China and Iran are increasingly targeting systems behind the UK’s key services, according to a warning this year from Richard Horne, the NCSC’s chief executive.

The government said last month the UK was “ready to defend itself” after Iran’s military warned any bases being used by the US were “legitimate targets”.

The UK has allowed the US to launch so-called defensive operations from British bases hosting American planes since the start of its war on Iran but has refused to help in offensive operations. That policy has not been altered by the new prime minister, Andy Burnham, who was notified last week that a decision had been made to extend the agreement with the US.

Iran’s Islamic Revolutionary Guard Corps (IRGC) said last month that “any base used for aggression against Iranian territory constitutes a legitimate target for our forces”.

Iran has been accused for years of carrying out cyber-attacks on various countries, including in relation to a massive power outage in Turkey in 2015 and several possible breaches of Israeli government websites in 2022.

US government security agencies issued a warning earlier this year of cyber-attacks on critical infrastructure by hackers linked to the IRGC.

The US has alleged that an Iran-affiliated group known as “CyberAv3ngers” carried out a campaign against it in 2023 that compromised at least 75 devices in multiple infrastructure sectors.