LONDON (Reuters) – Britain said on Monday that it and its partners held Chinese state-backed groups responsible for “a pervasive pattern of hacking” involving attacks on Microsoft Exchange servers.

The attacks took place early this year and affected more than a quarter of a million servers worldwide, the British foreign ministry said.

“The cyber attack on Microsoft Exchange Server by Chinese state-backed groups was a reckless but familiar pattern of behaviour,” British foreign minister Dominic Raab said in a statement.

“The Chinese Government must end this systematic cyber sabotage and can expect to be held account if it does not.”

The foreign office said the attack was “highly likely to enable large-scale espionage”.

It added Britain and its allies attributed the Chinese Ministry of State Security as being behind the hacking groups known by security experts as “APT40” and “APT31”.

(Reporting by William James and Michael Holden)