Boris Johnson, the Conservative Mayor of London, has been plotting to remove Britain’s most senior policeman because of his links with a businessman who won £3 million of Scotland Yard contracts.

Leaked e-mails obtained by The Times reveal that Mr Johnson’s aides wanted to suspend Sir Ian Blair, Commissioner of the Metropolitan Police, pending an inquiry into allegations of impropriety.

The move prompted angry internal exchanges, with Kit Malthouse, the deputy mayor, writing to one official: “Essentially it’s the mayor’s decision to suspend or not.”

Lawyers had to tell Mr Johnson’s team that it did not have the power to suspend Sir Ian. David Riddle, the Metropolitan Police Authority’s legal adviser, said: “If there is to be action against the commissioner, it has got to be lawful . . . If the nuclear button is pressed, expect it to be crawled over for legal flaws.”

Mr Riddle, who described the situation as “uniquely serious”, asked for his legal advice to be shown to the mayor. The lawyer said that he also expected Jacqui Smith, the Home Secretary, and her officials to be “in the loop” and for the Independent Police Complaints Commission to be kept informed.

Sir Ian is also fighting allegations of racism made by his most senior Asian officer, Assistant Commissioner Tarique Ghaffur, and next month an inquest into the shooting of Jean Charles de Menezes is expected to expose serious failures within the Met.

The commissioner and the mayor have appeared together at a number of events and spoken of building “a working relationship”. But the exchange of e-mails over the weekend shows that the Conservatives, who view Sir Ian as “new Labour’s favourite cop”, remain determined to try to remove him from Scotland Yard.

The Tories called for Sir Ian’s resignation last year after the Met was convicted of breaching health and safety laws over Mr de Menezes’s shooting. Mr Johnson supported those resignation calls and has had a tense relationship with Sir Ian since he told The Times, before his election as mayor, that he would have to work with the commissioner because he did not have the power to dismiss him.

He said last month that the mayor should be allowed to hire and fire the head of Scotland Yard, complaining that there was a “democratic deficit” in the present arrangements.

Mr Johnson intends to take over as chairman of the Metropolitan Police Authority in October and says that he will get “directly involved with day-to-day scrutiny of the police”.

The Metropolitan Police Authority’s professional standards committee met in secret on Monday morning to discuss an auditor’s report into the allegations against Sir Ian. It is understood that the issue of suspension was discussed and rejected.

Instead, the committee asked the Home Secretary to appoint an external investigator to examine the award of Scotland Yard contracts to Impact Plus, a consultancy that was run until last year by Andy Miller, 54, who has known Sir Ian for 30 years and accompanied him on skiing trips.

Sir Ian has denied any impropriety in his relationship with Mr Miller. He informed the Met and the Metropolitan Police Authority of his friendship with the businessman in November 2002 and says that he has been open and straightforward about the situation.

The decision on who will conduct the investigation into the contracts is understood to have been delayed because Ms Smith and senior officials are on holiday. Sources indicated, however, that Sir Ronnie Flanagan, the Chief Inspector of Constabulary, was the most likely candidate. Sir Ronnie is one of the few officers of sufficiently senior rank to conduct an inquiry into the Commissioner of the Met.

Mr Malthouse denied last night that he was plotting against Sir Ian, and said that he was merely investigating the “accountability and methodology” of the procedure. “These are internal e-mails asking what might or might not happen in a hypothetical situation – it’s nothing more than that,” he said. “I’ve been in the job six weeks so I guess I was querying whether it was appropriate to go there [the professional standards subcommittee].”

He said the issue of suspension was raised as “the possibility of what might happen in the future” and added: “That doesn’t mean that it was actively under consideration.”

He said that both he and Mr Johnson believed that the mayor should have a significant say over policing issues.

A spokeswoman for Mr Johnson said last night: “Boris Johnson hasn’t had any meetings or conversations about the future of Sir Ian Blair and awaits the outcome of any investigation. He continues to work with Sir Ian in fighting knife crime in London.”

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