Russian hackers reportedly read Obama's unclassified emails

Emails to and from President Barack Obama were read by Russian hackers in a breach of the White House's unclassified computer system, The New York Times said.

Earlier this month, US officials admitted there was a cyber "event" late last year, but refused to confirm reports Russia was behind the attack.

However the incursion was "far more intrusive and worrisome" than publicly acknowledged, the newspaper said, citing senior American officials briefed on the investigation, and saying the hackers were presumed to be linked to - or even working for - Moscow.

The hackers, who also got into the State Department's unclassified system, obtained access to the email archives of people inside the White House, and perhaps some outside, with whom Obama regularly communicated, the Times said. It was from those accounts that they reached emails that the president had sent and received, according to the officials.

The hackers did not appear to have penetrated the servers that control the message traffic from Obama's BlackBerry, and the White House has said that no classified networks were compromised.

"But officials have conceded that the unclassified system routinely contains much information that is considered highly sensitive: schedules, email exchanges with ambassadors and diplomats, discussions of pending personnel moves and legislation, and, inevitably, some debate about policy," the Times reported.