Andrew McCabe, the former FBI deputy director fired by the US attorney general, kept personal memos regarding President Donald Trump, according to a source.
The source said the memos are similar to the ones maintained by former FBI director James Comey, who Mr Trump fired last May, according to the Associated Press.
Mr Comey’s series of notes detailed interactions with Mr Trump that Mr Comey said unnerved him.
Mr McCabe’s memos include details of interactions with the president, among other topics, the source said.
It is not immediately clear whether any of the reported McCabe memos have been turned over to special counsel Robert Mueller or requested by Mr Mueller.