FBI agent Peter Strzok, who was removed from the probe into Russian interference in the 2016 US presidential election after it was revealed he had exchanged anti-Trump text messages with his lover, has been fired.

Aitan Goelman, Mr Strzok’s lawyer, said the 21-year veteran of the Federal Bureau of Investigation was fired by FBI deputy director David Bowdich on Friday.

Mr Goelman said Mr Strzok was dismissed despite the fact that the disciplinary office had decided he should face a demotion and a 60-day suspension.

He described the move as “a departure from typical bureau practice”.

“This decision should be deeply troubling to all Americans,” Mr Goelman said in a statement.

“A lengthy investigation and multiple rounds of congressional testimony failed to produce a shred of evidence that Special Agent Strzok’s personal views ever affected his work,” he said.

“In fact, in his decades of service, Special Agent Strzok has proved himself to be one of the country’s top counterintelligence officers.”

Mr Goelman claimed the decision to terminate was taken in response to political pressure, and “to punish Special Agent Strzok for political speech protected by the First Amendment, not on a fair and independent examination of the facts”.

“It is a decision that produces only one winner — those who seek to harm our country and weaken our democracy,” the lawyer said.

Mr Strzok, 48, and his lover, former FBI lawyer Lisa Page, exchanged text messages during the 2016 election campaign which were critical of then Republican nominee Donald Trump.

In the messages, he called Mr Trump a “disaster” and said “We’ll stop” a Trump candidacy.

Following the public revelation of the messages, Mr Strzok was removed by Special Counsel Robert Mueller from the investigation into Russian meddling into the 2016 election.

Mr Trump has seized upon the messages to bolster his claim that the Special Counsel’s probe is a political “witch hunt” by biased prosecutors.