Russian hackers who infiltrated the White House's unclassified computer system last year reportedly obtained access to some of President Obama's email correspondence, forcing officials to meet nearly daily for weeks afterward.

The New York Times reported Saturday that the hackers obtained an undisclosed number of Obama's emails, though their sensitivity is unclear and the president's email account itself appears to have escaped the hack.

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The guarded servers for Obama's BlackBerry, which he uses constantly to communicate with top aides, do not appear to have been penetrated in the hack, according to the Times, which also hit the State Department.

Earlier this month, CNN reported hackers linked to the Russian government had obtained a copy of Obama's schedule, including information not publicly available nor in general schedules given to media.

White House press secretary Josh Earnest declined at the time to identify who was behind the attack, saying "our investigators have concluded that it's not in our best interests to identify the entity that may be responsible."

Officials had told CNN the hackers were able to break into the White House through a foothold at the State Department, which had been for months battling its own cyber intrusion.

“It’s the Russian angle to this that’s particularly worrisome,” another senior official told the Times for its report.

The hack had come as the U.S. continues to face renewed frostiness with Russia due to its annexation of Crimea and upped military presence in and near Ukraine.

“This has been one of the most sophisticated actors we’ve seen,” one senior American official briefed on the investigation told the Times, which reported senior White House officials have known the hack's depth for months.

Russia, a key adversary of the U.S. in cyberspace, is believed to have found its way into most areas of critical U.S. infrastructure, including putting malware on software in the oil and gas pipeline industries and for wind turbines.

On Thursday, Pentagon chief Ashton Carter disclosed that Russian hackers had broken into unclassified networks at the Department of Defense earlier this year, but were quickly identified and thrown off the network.

Saturday's newest public revelation comes as Obama heads to the White House Correspondents' dinner, an annual Washington, D.C., bash that brings together politicians, members of the media and various celebrities.