The Department of Justice's internal watchdog is investigating James Comey for leaking classified information by sharing memos about his meetings with Trump with a friend, it has been reported. 

On Friday, The Wall Street Journal reported that the infamous memos and how the ousted FBI director leaked them were part of an ongoing probe by the inspector general. 

Comey's treatment of them, including him giving them to the media, is part of the investigation,  it was reported. 

The revelation prompted a tweet from the president, who previously dubbed Comey a 'leaker and a liar'.