(Reuters) -Microsoft Corp ( MSFT ) is informing some of its customers that a Russian state-sponsored hacking group breached its internal systems and accessed their emails, Bloomberg News reported on Thursday, citing a company spokesperson.

The technology giant is also providing previously notified clients with details of which data was taken, the report said.

Microsoft ( MSFT ) did not immediately respond to a request emailed by Reuters for comment and calls to spokespersons went unanswered.

The company had said in January, too, that a Russian state-sponsored group had hacked into its corporate systems and stolen some emails and documents from staff accounts.