Bernard Hogan-Howe, the Metropolitan Police commissioner, has pledged there will be a 'ruthless search' for the truth in the 'plebgate' row that lost former chief whip Andrew Mitchell his job.

Bernard Hogan-Howe, Andrew Mitchell and David Cameron (Reuters)

Mr Hogan-Howe cut short his holiday to return to work "because of concern for the welfare of all officers and their families involved in the events surrounding the Downing Street incident".

In a statement on Sunday he outlined the actions being taken by the Metropolitan Police over suggestions that accounts in police logs of an incident, in which the former chief whip was accused of calling officers "plebs", may have been falsified.

He said: "The allegations in relation to this case are extremely serious. For the avoidance of doubt, I am determined there will be a ruthless search for the truth - no matter where the truth takes us.

"This is shown not only by words but by action taken immediately following the receipt of new material earlier this month."

He pointed out actions being taken by the force to investigate the claims, and "maintain public confidence" in the police - including that he had appointed his deputy police commissioner, Patricia Gallan, to oversee the investigation, allocated 30 officers to the case and made arrests.

He also asked for the media not to pursue officers in the case because of the "significant pressure" it creates for the investigation.

"During the last 24 hours I have taken the opportunity to satisfy myself about the welfare of the officers involved. Media interest is to be expected, but for officers to be pursued and identified by the media during an ongoing investigation does, of course, create significant pressure," he said.

"I recognise that there is a great deal of public interest in these events. It is the investigating team who are in the best place to gather and assess all the evidence and it is vital that they are given the time and space to do this."

Defending Cameron

Mr Hogan-Howe's return comes as Downing Street issued a statement defending the way in which David Cameron handled the 'plebgate' row.

The prime minister has faced criticism for not sharing CCTV evidence, revealed by a Channel 4 News/Dispatches investigation last week, which cast doubt on accounts of the incident. Mr Cameron has been accused by some allies of Mr Mitchell of leaving the former chief whip "swinging in the wind".

Mr Mitchell has consistently denied using the word "pleb" after officers refused to let him cycle through the main gates to Downing Street, though has admitted he swore during the incident. Accounts in the police log of the incident said that Mr Mitchell had used the word.

The CCTV evidence has casted doubt on those accounts. Two men were arrested last week in connection with an investigation of the incident.

Dispatches and Channel 4 News investigation: see the CCTV footage yourself

On Sunday, Number 10 said Mr Cameron had stood by his colleague, had only accepted his resignation with "reluctance", and has "deep sympathy" for Mr Mitchell.

"Deep sympathy"

"The prime minister has deep sympathy for Andrew Mitchell after allegations emerged that a serving police officer fabricated evidence against him," Number 10 said.

"The prime minister stood behind his chief whip through weeks of growing demands to sack him. It was only when it became clear that he could no longer do his job that his resignation was accepted with reluctance.

Andrew Mitchell "plebgate" row: the key questions

"Andrew Mitchell did not disagree with the prime minister's approach throughout this period. The prime minister, and Andrew Mitchell, were deeply shocked to be informed that the police were investigating allegations that a serving police officer had lied about the events."

Asked this week whether Mr Mitchell could make a comeback, Mr Cameron said: "One step at a time. Let's get to the truth about what happened.

"But I think it has been an extraordinary development, frankly, to find a police officer apparently posing as a member of the public, pretending to have been outside Downing Street at the time and then trying to blacken the name of a cabinet minister."

"Awful toxic phrases"

Mr Mitchell has been intensifying efforts to clear his name over the allegations. In an interview with The Sunday Telegraph he said: "These awful toxic phrases which were hung round my neck for weeks and weeks in a sustained attempt to toxify the Conservative Party and destroy my career were completely and totally untrue.

He added: "If you had told me on 19 September (the day of the altercation) that the events revealed last week could take place in Britain today, I simply would not have believed you."