Downing Street has resisted calls for an inquiry into Chief Whip Andrew Mitchell, after the Cabinet minister apologised publicly to police officers for subjecting them to a tirade of verbal abuse in Downing Street.
David Cameron's official spokesman said the Prime Minister believes that Mr Mitchell had done the right thing in apologising, and thinks a line should now be drawn under the affair.
But a senior Police Federation representative said Mr Mitchell was effectively accusing the officers involved of lying and called on Mr Cameron to hold an investigation.
Labour too called for an inquiry, while Deputy Prime Minister Nick Clegg said it was right that Mr Mitchell should explain "fully and in detail" what happened during the altercation after officers refused to allow him to cycle through the main gates of Downing Street.
The Sun, which broke the original story, reported that it had now seen a police report of the incident, prepared for senior officers, which indicated that Mr Mitchell called the officers "plebs" as well as swearing repeatedly at them.
The report was said to be backed up by at least two officers making the same verbatim note of the exchange in their pocket books but in his first appearance before the cameras since news of his outburst broke last week, Mr Mitchell insisted that reports of his comments were inaccurate.
Asked whether he had used the politically explosive word "plebs", he said: "I want to make it absolutely clear that I did not use the words that have been attributed to me."
Speaking as he arrived for work in Whitehall, Mr Mitchell acknowledged that he had not shown the police "the amount of respect I should have done" during the confrontation, adding: "I have apologised to the police, I have apologised to the police officer involved on the gate and he's accepted my apology and I hope very much that we can draw a line under it there."
However, the chairman of the Metropolitan Police Federation, John Tully, said Mr Mitchell was effectively accusing the officers of lying and called on Mr Cameron to hold an investigation.
Scotland Yard is investigating how The Sun newspaper came to be in possession of internal police information. A spokeswoman said: "We are aware of this. The Directorate of Professional Standards has been informed. Inquiries into the circumstances are being carried out."