The FBI fired Agent Peter Strzok — at one time one of the leaders of the bureau’s investigation into Russian election meddling and possible collusion with Donald Trump’s campaign — for writing critical text messages about the future president, the Washington Post reported Monday.

Aitan Goelman, Strzok’s lawyer, told the paper that FBI Deputy Director David Bowdich ordered that Strzok be canned on Friday — even though the head of the FBI office that usually metes out discipline had ruled Strzok should face only a demotion and 60-day suspension.

Goelman said the move undercuts the FBI’s assurances that Strzok would go through the normal disciplinary process.

“This isn’t the normal process in any way more than name,” Goelman said.

Trump took to Twitter to gloat about the agent’s termination — and once again slam the bureau.

“Agent Peter Strzok was just fired from the FBI – finally. The list of bad players in the FBI & DOJ gets longer & longer. Based on the fact that Strzok was in charge of the Witch Hunt, will it be dropped? It is a total Hoax. No Collusion, No Obstruction – I just fight back!” he said.

The president also said his firing should mean that the probe into Hillary Clinton’s email server — which Strzok oversaw — should be reopened.

“Just fired Agent Strzok, formerly of the FBI, was in charge of the Crooked Hillary Clinton sham investigation. It was a total fraud on the American public and should be properly redone!” he wrote.

Strzok was removed from the feds’ probe into Russia and Trump by special counsel Robert Mueller after texts critical of Trump that he sent to his then-lover, FBI lawyer Lisa Page, were discovered.

Strzok, a 22-year veteran of the FBI, had already been a frequent target of President Trump’s Twitter tirades.

“Russian Collusion with the Trump Campaign, one of the most successful in history, is a TOTAL HOAX. The Democrats paid for the phony and discredited Dossier which was, along with Comey, McCabe, Strzok and his lover, the lovely Lisa Page, used to begin the Witch Hunt. Disgraceful!” he tweeted on Aug. 1 in a typical post.

Trump has also mocked Strzok and Page as “FBI lovers,” and exploited their relationship and anti-Trump views to try to discredit Mueller’s ongoing probe.

”Will the FBI ever recover it’s once stellar reputation, so badly damaged by Comey, McCabe, Peter S and his lover, the lovely Lisa Page, and other top officials now dismissed or fired? So many of the great men and women of the FBI have been hurt by these clowns and losers!” he tweeted on Saturday.

FBI Inspector General Michael Horowitz wrote after probing Strzok and Page that Strzok showed a “willingness to take official action” to hurt Trump, citing a text he sent telling Page “we’ll stop” Trump from getting elected.

Testifying before the House Judiciary and Oversight and Government Reform committees last month, Strzok did not deny that he held deep animus toward the president — but that his personal bias did not affect his work.

Horowitz reached the same conclusion.

Strzok told lawmakers that there was “no evidence of bias in my professional actions” and that his having to testify was “just another victory notch in [Russian President Vladimir] Putin’s belt and another milestone in our enemies’ campaign to tear America apart.