The investigation into the Andrew Mitchell "plebgate" row must be "rigorous and thorough" if it is to restore the public's faith in the police, the head of the Police Federation has said.
Paul McKeever, the organisation's Chairman, admitted the revelations an officer had posed as a member of the public to give false evidence against Mr Mitchell had damaged the reputation of the force.
Officers are now examining the allegations, along with the possibility of a "conspiracy" to smear Mr Mitchell as part of a "large scale and complex investigation".
Mr Mitchell was forced to resign as Tory Chief Whip over a clash with a police officer at Downing Street in which, it was alleged, he called the policeman a "pleb".
Speaking to Sky News' Crime Correspondent Martin Brunt Mr McKeever said that although he had not called for Mr Mitchell's resignation, he had come close and admitted with hindsight he may have done things differently.
But he said that feelings were running high in the aftermath of the shooting of two police officers in Manchester on the week of Mr Mitchell's altercation with the policeman.
He added that recent events had revealed an "astonishing set of circumstances".
"If a writer was to put this down on paper they would be accused of being melodramatic but there are some extraordinary things that have happened over the last few days.
"The important thing is that there is a proper, thorough investigation that takes place to find out what's happened so that the British public can still have trust in the police service," he said.
His comments come after Scotland Yard arrested a second man in connection with their inquiry and searched the home of both him and the police officer in question.
The 23-year-old was held on suspicion of intentionally encouraging or assisting the commission of an indictable offence on or around December 14.
He is neither a police officer nor a member of police staff but the arrest relates to claims by the officer to have witnessed the clash in Downing Street, Scotland Yard said.
The serving police officer was arrested on December 15 on suspicion of misconduct in public office in connection with the affair.
The Met Police now have 30 officers working on an investigation into the row after widening their probe when new revelations emerged.
Mr Mitchell has insisted he was the victim of a "stitch-up" and is pushing for a full inquiry.
CCTV footage which appeared to conflict with the official police log of the altercation, which was leaked to the press, is being scrutinised.
Prime Minister David Cameron has described allegations that an officer tried to "blacken the name of a Cabinet minister" as a "very serious issue".
The officer allegedly wrote an email to his local MP, Conservative John Randall, posing as a member of the public and accusing Mr Mitchell of calling police "plebs".
The account in the email, which was written the day before the story first appeared in the press, was very similar to the police log which was also later leaked.
Littered with grammatical errors, spelling mistakes, capital letters and malapropisms, it was passed to Downing Street on September 25.
According to Channel 4 News, the writer claimed he had been walking past with his nephew and recognised Mr Mitchell.
"Imagine our horror when we heard MR MITCHELL shout very loudly at the police officers guarding YOU [expletive blacked out] PLEBES!! and "YOU THINK YOU RUN THE [expletive blacked out] COUNTRY" and just continued to shout obscenities at the poor police officers," he wrote.
Mr Mitchell has admitted swearing at police but insists he never said the word "plebs" - a word that was seized on by Labour and the Police Federation.
The email allegedly helped fuel the row and keep up the momentum that eventually forced the MP to stand down several weeks later.
At the time, Cabinet Secretary Sir Jeremy Heywood compared the email's claims to the CCTV footage. He decided they were not "reliable" but did not look at the police log.
There is speculation Mr Mitchell could be restored to the front bench, depending on the results of the police investigation.