The incident is believed to be the first known instance of hackers affiliated with the Iranian regime successfully shutting down such a facility in the UK. It is also being described as one of the most significant cyberattacks of its kind, The Telegraph reported.
According to the British newspaper, the incident may have occurred around the same time as a series of cyberattacks targeting US water infrastructure last month. The attacks affected facilities across 12 states and reportedly raised concerns at the White House.
British officials have declined to identify the power plant involved, citing security concerns. However, the facility is understood to have been taken offline for four days while staff worked to restore operations, the report said.
The plant was reportedly relatively small, and the incident did not affect the UK's wider electricity supply or overall energy generation.
The incident was also reportedly reported to the National Cyber Security Centre (NCSC), the public-facing cybersecurity arm of Britain's GCHQ, which provides guidance to organisations on protecting critical national infrastructure from foreign cyber threats.
The reported incident comes amid similar cyberattacks against US water infrastructure last month.
Dozens of wastewater treatment facilities across the US were reportedly targeted, resulting in flooding, reduced water pressure and boil-water advisories in some communities.
Minnesota reported the first such incident, followed by similar attacks in Michigan, Georgia, South Dakota and New Jersey.