Police were right to threaten Mitchell with arrest, says Boris

Boris Johnson has spoken out to back the police in the Andrew Mitchell 'gate-gate' scandal.

Claiming police were right to threaten the senior Tory with arrest, the London Mayor said it was "wholly commonsensical" due to the "gravity of this offence".

Commending Mr Mitchell's apology however he said: "The crucial thing for me is that Andrew Mitchell has now apologised not just once but twice.

"He's also apologised to the police officer concerned and that underscores how wrong it is for any us to abuse police officers."

The comments will likely be viewed as an untimely intervention from the mayor, just the day after David Cameron and cabinet secretary Jeremy Heywood agreed there was no need for further investigation.

Mr Johnson voiced his opinion during the opening of a library in Ruislip, South London - re-igniting the debate on an issue the prime minster had hoped to lay to rest.

Pressure on Mr Mitchell intensified after The Daily Telegraph published the full 442-word police log of the incident, which showed he called officers "plebs" and swore at them repeatedly.

Mr Mitchell continues to insist he did not use the words attributed to him - prompting angry complaints from the Police Federation that he was effectively accusing the officers involved of lying.

Deputy Prime Minister Nick Clegg resultantly called on the chief whip to 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.

This is something the Tory MP has so far failed to do sparking calls for an official investigation.

Speaking to Sky News, John Tully, chairman of the Metropolitan Police Federation said: "I think the Prime Minister or Downing Street officials should hold an inquiry and if Mr Mitchell is proved to have lied, then he should be sacked."

The ruling out of such an inquiry by the prime minister has led Labour's Yvette Cooper to accuse the PM of staging a cover-up.