Britain has not recorded and has no evidence that networks at the Sellafield nuclear site were the targets of a successful cyber attack, the government said on Monday, after The Guardian reported that cyber groups with close links to the Kremlin and Beijing had breached computer systems. Reuters reports.

The Guardian reported that Sellafield, a nuclear fuel reprocessing, storage and decommissioning company, was hacked by cyber groups with close ties to Russia and China.

“Our monitoring systems are robust and we have a high degree of confidence that there is no such malware on our system,” the government said.

“This was confirmed by The Guardian well in advance of publication, along with denials of a number of other inaccuracies in their story.”

Sellafield, which is controlled by the government’s Nuclear Decommissioning Authority, is located in north-west England and employs 11,000 people.

In a separate statement, the UK’s Office of Nuclear Regulation (ONR) also said it saw no evidence that state actors had hacked its systems, The Guardian reported.

But the regulator said Sellafield does not currently meet certain high cyber security standards it requires, adding that it has put the plant under “significantly increased scrutiny”.

“Some specific issues are the subject of an ongoing investigation process, so we cannot comment at this time,” ONR said.

The Guardian wrote that the ONR is likely to be preparing to sue the people in Sellafield over the cyber failures.