(CNN) Former FBI General Counsel James Baker is under criminal investigation for leaks, according to new information released by Republicans on the House Oversight Committee.

Two of President Donald Trump's Republican allies on Capitol Hill are raising questions about a leak investigation involving Baker in a letter to the Justice Department on Tuesday. Baker has become a central focus of some Republicans recently as his closed-door testimony to lawmakers last fall confirmed that top officials at the FBI were concerned that the President may have been working to benefit Russia, particularly after the firing of FBI Director James Comey.

In a letter to US Attorney John Durham, Reps. Mark Meadows and Jim Jordan of the conservative House Freedom Caucus cite a previously undisclosed portion of Baker's transcript where his lawyer interjected to say: "he's been the subject of a leak investigation that is ... still active at the Justice Department."

The lawyer then went on to caution where Baker's discussions with reporters came up. Asked if this was a criminal investigation by Meadows, Baker's attorney replied "yes."

Meadows and Jordan, the top Republican on the House Oversight Committee, go on to request more information about the probe in their letter, saying that they run the risk of inadvertently interfering as they investigate the FBI's actions in 2016 without knowing more.

Read More