Russian hackers reportedly obtained US President Barack Obama's emails when there was a cyberattack on White House's unclassified computer system last year.
According to Fox News, the report indicated that the breach was significantly more intrusive than originally thought.
Citing officials briefed on the investigation that the hackers managed to obtain access to email archives of people with whom Obama communicated.
Obama's email account itself does not appear to have been hacked but officials said that the unclassified system often contains highly sensitive information that includes schedules, email exchanges with ambassadors and diplomats, and debates about policy and legislation.