Ex-FBI deputy director, Andrew McCabe has given memos about conversations he had with President Donald Trump to an inquiry into alleged Russian meddling in the 2016 election, US media say.
They say the memos could support allegations that the president sought to obstruct justice.
Mr McCabe was fired from the FBI on Friday following an internal inquiry and Mr Trump had accused him of bias.
The president has also dismissed the Russia investigation as a “witch hunt”.
The investigation is led by special counsel Robert Mueller, himself a former FBI director.
He has so far indicted 19 people.