David Cameron was tonight urged to “urgently” review evidence around Chief Whip Andrew Mitchell's alleged foul-mouthed outburst at Downing Street police officers.
The Prime Minister was told by Labour to "get to the truth".
Mr Cameron was also told to take responsibility for the Tory enforcer's behaviour by the widow of murdered police officer Sharon Beshenivsky.
Police have suggested Mr Mitchell was close to being arrested after allegedly shouting "learn your f*****g place" and calling officers "plebs" when he was stopped from cycling out of Downing Street's main gates.
Although the former shadow police minister has apologised for not treating officers with due respect he has denied using some of the language reported.
Conservative Nick de Bois warned that Mr Mitchell was in "deep trouble" if evidence emerged supporting the officers' version of events.
Labour called on the PM to take swift action to uncover the truth about the tirade, including examining Downing Street CCTV footage.
Shadow police minister David Hanson said: "The Prime Minister needs to review urgently Andrew Mitchell's version of events versus what the police officers have said.
"I'm asking for the PM to look at it, talk to Andrew Mitchell, clarify what he said.
"There will be clear evidence available, CCTV evidence, that could establish the truth.
"This is the second day there has been a question mark over the events of that day. It is not good for the Government to have this hanging over it."
John Tully, chairman of the Metropolitan Police Federation, said there was a written account of the incident in the notebooks of the officers from the Scotland Yard Diplomatic Protection Group, known as SO6.
He said: "He should resign. As a Cabinet Minister it's unacceptable for someone of his standing to use such disrespectful and abusive language to a police constable let alone anyone else."
David Cameron dodged questions about whether he planned to sack Mr Mitchell and condemned his behaviour as "wrong" and "inappropriate".
"What Andrew Mitchell said and what he did was not appropriate. It was wrong and it is right that he has apologised," he said.
"He has obviously apologised to me, but more importantly he has apologised thoroughly to the police and that needed to be done."
Liberal Democrat president Tim Farron said the comments, as reported, were "beyond unacceptable".
"If he said what it is reported he said, it is absolutely appalling," he told the BBC.
"All of us can have grouchy moments and say things we regret but it reveals, what he is reported to have said, something not terribly pleasant.
"Having said that, a lot of this stuff is still yet to be revealed. It is David Cameron's job to discipline his minister in the same way that if it was the Liberal Democrat chief whip, who I am sure would never do a thing like this, it would be Nick Clegg's job.
"But certainly the comments reported are utterly, indeed beyond, unacceptable."
Mr de Bois, asked about the situation after a guest appearance on the fringes of the Liberal Democrat conference in Brighton, said: "If it turns out that he said these words then he is in deep trouble."
Ken Clarke, minister without portfolio, and senior Tory backbencher David Ruffley defended Mr Mitchell.
Mr Clarke said: "I have known Andrew for a long time and he is a perfectly reasonable, courteous man with the same high regard for the police services as anyone else.
"He obviously had a flare of bad temper on this occasion and has rightly apologised. I do think this should be allowed to set the matter at rest."
Mr Ruffley said: "I have known Andrew Mitchell since he became shadow police minister, a post I subsequently held," he said.
"So I can attest to the fact that he has the highest regard for the police service of this country.
"As a strong supporter of tough, traditional law and order policies, Andrew understands the central importance of police officers in fighting crime and keeping us safe.
"Nothing that may have occurred this week should affect his well-deserved reputation for being on the side of policemen and policewomen."
Mr Mitchell, who was also a minister under John Major in the early 1990s, apologised in a statement.
The MP for Sutton Coldfield said: "On Wednesday night I attempted to leave Downing Street via the main gate, something I have been allowed to do many times before.
"I was told that I was not allowed to leave that way. While I do not accept that I used any of the words that have been reported, I accept I did not treat the police with the respect they deserve.
"I have seen the supervising sergeant and apologised, and will also apologise to the police officer involved."
Mr Mitchell, a keen cyclist, was reported by the Sun to also have called the police "morons".
"Best you learn your f*****g place. You don't run this f*****g Government. You're f*****g plebs," it reported him as saying.Reuse content