Andrew Mitchell, the MP for Sutton Coldfield, has denied calling a police officer a "pleb" during an altercation in Downing Street.

Mr Mitchell reiterated his apology after not showing the police "the amount of respect I should have done" during the confrontation last week.

But asked if he called the officer a "pleb", he said: "I want to make it absolutely clear that I did not use the words attributed to me."

Questioned by reporters as he arrived for work in Whitehall, Mr Mitchell refused to be drawn on what he actually said to the officer.

"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," he said.

Earlier however, Deputy Prime Minister Nick Clegg stepped up the pressure, insisting that Mr Mitchell must provide a full account of what happened after The Sun reported that police logbooks showed he called officers "plebs" and swore repeatedly.

Mr Mitchell described the incident as taking place at the end of "a long and extremely frustrating day - not that that is any excuse at all for what happened," he said. "I didn't show the police the amount of respect I should have done. We should all respect the police, they do an incredibly difficult job."

However he made clear that he was determined to resist calls for his resignation. He said: "I am now going to go in and get on with my work. Thank you very much indeed."