"That's it?" Comey said on Twitter.
"Dishonest and misleading memo wrecked the House intel committee, destroyed trust with Intelligence Community, damaged relationship with FISA court, and inexcusably exposed classified investigation of an American citizen. For what?" Comey wrote, adding: "DOJ & FBI must keep doing their jobs."
The tweet was the latest in a series from Comey this week as Trump clashed with the FBI over the release of the GOP- written memo.
"All should appreciate the FBI speaking up. I wish more of our leaders would," Comey tweeted Thursday night amid news that the FBI had lobbied the White House to block the release of a partisan memo on the Russia investigation.
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On Friday morning, the president continued his verbal attacks against the FBI, writing on Twitter, "The top Leadership and Investigators of the FBI and the Justice Department have politicized the sacred investigative process in favor of Democrats and against Republicans -- something which would have been unthinkable just a short time ago. Rank & File are great people!"
Trump and Republicans on the House intelligence committee followed up on those attacks through the publication yesterday of a GOP-authored memo that they say shows improper use of surveillance by the FBI in the initial stages of the investigation.
The FBI, Justice Department and Democrats furiously lobbied Trump to stop the release, saying it could harm national security and mislead the public.
On Twitter, Comey urged his former colleagues to "take heart: American history shows that, in the long run, weasels and liars never hold the field, so long as good people stand up."
Since his firing last May, Comey has made his personal feelings about Trump known, testifying in detail about personal interactions he says troubled him.
He also authorized a close friend to share with reporters details from a memo he produced documenting one such encounter -- a February conversation in the Oval Office in which he said Trump encouraged him to drop an FBI investigation into former national security adviser Michael Flynn.
Comey has also used language about "weasels" before, most notably in a September 2016 congressional hearing when he defended the FBI's handling of the Hillary Clinton email investigation.
"You can call us wrong, but don't call us weasels," Comey said. "We are not weasels. We are honest people and we did this in that way.