I'll pick new Met chief alone, Smith tells Mayor

In a letter to the Mayor, Ms Smith rejects calls by Mr Johnson for the pair to jointly interview the candidate and claims choosing Sir Ian Blair's replacement in this way would breach rules set up to ensure a "fair and open" selection based on merit.

Ms Smith also snubs calls by the Mayor for a delay in the appointment process, saying that a hold-up would not be in the interests of Londoners or the country, and dismisses suggestions that an overseas candidate could be chosen.

She and the Mayor had uncompromising exchanges last week over Mr Johnson's role in forcing Sir Ian's resignation. At the weekend the Mayor wrote to Ms Smith calling for a "fairly lengthy consolidation period" before the next Commissioner was appointed.

The Mayor said such "a pause to take stock" would benefit the Met and added that he wanted to be involved in both the shortlisting and final interviewing of candidates to ensure the needs of Londoners taken into account.

In her reply, Ms Smith rejects all of his key demands. She says that while she will "have regard" to the views of the Mayor and the Metropolitan Police Authority, she will make the final decision on who to recommend to the Queen after conducting the final interviews alone. She rules out delaying the selection, saying: "My responsibilities for policing in London and the nation make it impossible for me to add undue delay before making a recommendation."

The letter further rejects suggestions that a foreign candidate, such as Los Angeles police chief Bill Bratton who met Mr Johnson two weeks ago, could be appointed. "We need an exceptional top police officer, who should be a UK citizen not least because of the counter-terrorism sensitivity of the post".

Adverts for the post are expected to be placed shortly and an initial shortlisting and interview process will be carried out by Home Office Permanent Secretary Sir David Normington, the director general of Office for Security and Counter-Terrorism Charles Farr, two members of the mpa and one more independent person.

Ms Smith says that following this process, Mr Johnson and the MPA will be able to "form your views" and pass them to the Home Office, but she will take the final decision.

Earlier today, Mr Johnson said it was "complete tripe" to suggest that he wanted to wait until a Tory home secretary was in place.