"This attack on my credibility is one part of a larger effort not just to slander me personally, but to taint the FBI, law enforcement, and the intelligence professionals," McCabe said.
The Associated Press reported Saturday that McCabe has kept memos regarding his interactions with President Trump.
In an earlier interview, McCabe rejected the allegations that he was untruthful during internal hearings, the Times reported.
“The idea that I was dishonest is just wrong,” he said.
“This is part of an effort to discredit me as a witness.”
McCabe is a potential witness in special counsel Robert Mueller's investigation into whether the Trump campaign colluded with Russia during the 2016 presidential campaign
Shortly after midnight, President Donald Trump tweeted about the firing, calling it “a great day for democracy.”
John Dowd, President Trump's personal attorney, told The Daily Beast on Saturday that he "prayed" that Deputy Attorney General Rod Rosenstein follows Sessions' example and brings an end to the Mueller probe.
McCabe, who had been with the FBI for 22 years, resigned his position in late January, but stayed on at the agency until he was eligible to retire on Sunday.