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.