A small power plant in the United Kingdom was shut down for four days in July following a cyberattack allegedly carried out by hackers linked to Iran.

The incident occurred around the same period that United States authorities, including the Federal Bureau of Investigation, warned of malicious cyber actors targeting water facilities in at least seven states, The Telegraph reported on Sunday.

The Cybersecurity and Infrastructure Security Agency, FBI, Environmental Protection Agency and other government agencies attributed those attacks to Iran-linked actors.

However, a U.K. government spokesperson declined to attribute responsibility for the reported power plant outage or disclose the identity of the facility.

The Department of Energy Security and Net Zero said it had briefed energy industry chief executives and written to companies with guidance on the next steps.

The department also said it was updating cybersecurity regulations.

Following the launch of U.S. and Israeli military operations against Iran on February 28, cybersecurity experts warned that Iranian-linked hackers could target American businesses and critical infrastructure.

On August 18, the U.S. Department of Justice charged 17 Iranians over what it described as a “massive cyber theft campaign” carried out on behalf of the Islamic Revolutionary Guard Corps and other Iranian entities.