Washington (AFP) - Donald Trump slammed the FBI as he hailed the firing of a veteran Bureau agent as a "great day for democracy," a move his attorney said he hoped would bring an end to a probe into alleged collusion between the president's campaign and Russia.
Critics described the axing of Andrew McCabe -- the deputy of former FBI director James Comey -- as a "dangerous" ploy to discredit the top US law enforcement agency as well as the work of Robert Mueller, the special counsel investigating Russian influence in the 2016 election.
McCabe is a potential key witness in the Russia probe.
Trump on Saturday via Twitter blasted the alleged "tremendous leaking, lying and corruption at the highest levels of the FBI, Justice & State."
He also reiterated long-running criticism of the Mueller investigation, terming it a "witch hunt" and saying that it "should never have been started in that there was no collusion and there was no crime."
- McCabe job offer -
Earlier, Trump's personal attorney, John Dowd, told the Daily Beast that he hoped Deputy Attorney General Rod Rosenstein would follow the lead of the FBI Office of Professional Responsibility and "bring an end to alleged Russia Collusion investigation manufactured by McCabe's boss James Comey based upon a fraudulent and corrupt Dossier."
Dowd told the Daily Beast he was speaking for the president. But in a subsequent statement he said he had been "speaking for myself, not the president."
McCabe, who has endured a year of withering attacks from Trump, was fired by the Justice Department late Friday, just two days before he was to retire after 21 years with the FBI.
Critics say the firing is a step in Trump's plan to engineer Mueller's dismissal, potentially sparking a constitutional crisis.
Mueller is also examining whether Trump might have obstructed justice, including by firing Comey last May.
One Democratic lawmaker, Mark Pocan of Wisconsin, announced Saturday that he offered McCabe a job in his office so he can complete the time necessary to retire with full federal benefits.
"My offer of employment to Mr. McCabe is a legitimate offer to work on election security," Pocan said in a statement.
McCabe spokeswoman Melissa Schwartz was non-committal. "We are considering all options," she told the Washington Post.
- 'War' on the FBI -
"Andrew McCabe FIRED, a great day for the hard working men and women of the FBI - A great day for Democracy," Trump tweeted soon after the firing.
McCabe denied any impropriety and said he was the victim of a Trump administration "war" against the FBI and the special counsel.
McCabe kept memos of his interactions with Trump, US media reported Saturday, adding that the documents could bolster his version of events.
Comey pushed back as well. "Mr President, the American people will hear my story very soon. And they can judge for themselves who is honorable and who is not," he tweeted.
The Justice Department said an internal investigation had found that McCabe made unauthorized disclosures to the media, and had not been fully honest "on multiple occasions" with the department's inspector general.
"The FBI expects every employee to adhere to the highest standards of honesty, integrity and accountability," Attorney General Jeff Sessions said in a statement.
Lack of candor under oath is a firing offense at the FBI, but the politically-charged context of the move raised questions among McCabe's backers.
Former CIA chief John Brennan lost his patience with Trump. "When the full extent of your venality, moral turpitude and political corruption becomes known, you will take your rightful place as a disgraced demagogue in the dustbin of history," he tweeted.
- 'Not political appointees' -
Trump, in an early afternoon tweet, belittled the media for its coverage of the story, saying: "The Fake News is beside themselves that McCabe was caught, called out and fired..."
In a second tweet he again denied any collusion with Russia.
Details of the inspector general's probe were not made public, but it involved the FBI's handling of the 2016 investigation into Trump's election rival, Democrat Hillary Clinton.
Trump has repeatedly accused McCabe and Comey of protecting Clinton from prosecution, including over her misuse of a private email server while she was secretary of state.
The inspector general's probe was "part of an unprecedented effort by the administration, driven by the president himself, to remove me from my position, destroy my reputation, and possibly strip me of a pension that I worked 21 years to earn," McCabe said in a statement.
"It is part of this administration's ongoing war with the FBI and the efforts of the special counsel investigation."
But one law professor defended the Justice Department's investigators.
"These are not political appointees," Jonathan Turley of George Washington University told CNN.
"They clearly concluded that McCabe misled them -- and that he misled them on one of the core issues they were investigating."
The White House has shown mounting frustration with the collusion probe, as it focuses ever more closely on the president's inner circle.