An embattled FBI agent whose anti-Trump text messages exposed the US justice department to claims of institutional bias has vigorously defended himself at an extraordinary congressional hearing that devolved into shouting matches, finger-pointing and veiled references to personal transgressions.

Peter Strzok testified publicly for the first time since being removed from special counsel Robert Mueller’s team following the discovery of texts last year that were traded with an FBI lawyer in the run-up to the 2016 presidential election.

In a chaotic hearing that spanned 10 hours, he insisted he had never allowed personal opinions to affect his work, though he did acknowledge being dismayed by Donald Trump’s behaviour during the campaign.

Peter Strzok
There were extraordinary exchanges during Mr Strzok’s testimony (AP)

Mr Strzok also said he had never contemplated leaking damaging information he knew about the Trump campaign.

He called the hearing “just another victory notch in Putin’s belt”, referring to Russian president Vladimir Putin.

“At no time, in any of those texts, did those personal beliefs ever enter into the realm of any action I took,” Mr Strzok told members of congress.

In breaking his silence, Mr Strzok came face-to-face with Republicans who argued that the texts had tainted two hugely consequential FBI probes he had helped steer: inquiries into Hillary Clinton’s email use and possible co-ordination between the Trump campaign and Russia.

“Agent Strzok had Hillary Clinton winning the White House before he finished investigating her,” said Trey Gowdy, Republican chairman of the House Oversight and Government Reform Committee.

Peter Strzok
Mr Strzok walks from the witness seat during a break in testimony (AP)

“Agent Strzok had Donald Trump impeached before he even started investigating him. That is bias.”

Republican Darrell Issa made Mr Strzok read some of his texts aloud, including some with profane language.

House Judiciary Committee Chairman Bob Goodlatte asked colleagues to imagine being investigated by someone who “hated you” and “disparaged you in all manner of ways”.

“Would anyone sitting here today believe that this was an acceptable state of affairs, particularly at an agency whose motto is ‘Fidelity, Bravery and Integrity’? I think not,” Mr Goodlatte said.

Strzok repeatedly insisted the texts, including ones in which he called Mr Trump a “disaster” and said “We’ll stop” a Trump candidacy, did not reflect political bias and had not infected his work.

Peter Strzok
Mr Strzok is sworn in (AP)

He said the Trump investigation originated not out of personal animus but rather from concern that Russia was meddling in the election, including what he said were allegations of “extraordinary significance” of a Russian offer of assistance to a Trump campaign member.

He made clear his exasperation at being the focus of a hearing when Russian election interference had successfully sown discord in America.

“I have the utmost respect for Congress’ oversight role, but I truly believe that today’s hearing is just another victory notch in Putin’s belt and another milestone in our enemies’ campaign to tear America apart,” Mr Strzok said.

The hearing brought to the surface a little-discussed reality of public service: Law enforcement agents and other government workers are permitted to espouse political views but are expected to keep them separate from their work. Mr Strzok said he was not alone in holding political opinions, noting that colleagues in 2016 supported both Mrs Clinton and Mr Trump, but did not reflect those views on the job.

“What I am telling you is I and the other men and women of the FBI, every day take our personal beliefs, and set those aside in vigorous pursuit of the truth — wherever it lies, whatever it is.”

Bob Goodlatte
Committee chair Bob Goodlatte questions Mr Strzok (AP)

To which Texas representative Ted Poe responded: “And I don’t believe you.”

Mr Strzok said under aggressive questioning that a much-discussed August 2016 text in which he vowed “we’ll stop” a Trump candidacy followed Mr Trump’s denigration of the family of a dead US service member.

He said the late-night, off-the-cuff text reflected his belief that Americans would not stomach such “horrible, disgusting behaviour” by the presidential candidate.

However, he added in a raised voice and emphatic tone: “It was in no way – unequivocally – any suggestion that me, the FBI, would take any action whatsoever to improperly impact the electoral process for any candidate. So, I take great offence, and I take great disagreement, to your assertion of what that was or wasn’t.”

Plus, he said, both the Clinton and Russia investigations were handled by large teams that “would not tolerate any improper behaviour in me any more than I would tolerate it in them”.

Mr Strzok drew applause when he said: “That is who we are as the FBI.

“And the suggestion that I, in some dark chamber somewhere in the FBI, would somehow cast aside all of these procedures, all of these safeguards and somehow be able to do this, is astounding to me. It simply couldn’t happen.”

The hearing exposed clear partisan divides in the House judiciary and oversight committees, as Democrats accused Republicans of trying to divert attention from Mr Trump’s ties to Russia by excessively focusing on Mr Strzok.

Democratic representative Steve Cohen of Tennessee said he would give Strzok a Purple Heart if he could. Representative Bonnie Watson Coleman said: “I have never seen my colleagues so out of control, so angry.”