LONDON - Britain's National Cyber Security Centre (NCSC) said on Thursday it was working with Microsoft to understand the impact of a wide-reaching Chinese hack which accessed email accounts used by senior U.S. government officials and agencies.

On Tuesday, Microsoft revealed that a stealthy Chinese hacking operation had exploited a secret flaw in a piece of its authentication software in order to covertly break into email accounts belonging to 25 unnamed organisations.

"We are working with Microsoft to fully understand the incident and UK impact," said a spokesperson for the NCSC, which is part of Britain's GCHQ spy agency.

  - Reuters