Microsoft Corp. said on Wednesday it will begin warning users of its Outlook.com email service when the company suspects that a government has been trying to hack into their accounts.

Microsoft told Reuters about the plan in a statement. It comes nine days after Reuters asked the company why it had decided not to tell victims of a hacking campaign, discovered in 2011, that had targeted international leaders of China's Tibetan and Uighur minorities in particular.

According to two former employees of Microsoft, the company's own experts had concluded several years ago that Chinese authorities had been behind the campaign but the company did not pass on that information to users of its Hotmail service, which is now called Outlook.com. In its statement, Microsoft said neither it nor the U.S. government could pinpoint the sources of the hacking attacks and that they didn't come from a single country.

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