Downing Street has insisted it had not approached anyone to be the next Metropolitan Police commissioner, following a report that Home Secretary Theresa May had effectively blocked an American "supercop" who was David Cameron's favoured candidate.
The Daily Telegraph reported that Number 10 approached Bill Bratton - former police chief in Boston, New York and Los Angeles - to see if he would be interested in taking on the job of leading London's police.
Mr Bratton - known for pioneering the "zero tolerance" philosophy of policing, cutting murder rates in New York and taking on LA's gang culture - is said to have signalled his interest, but his appointment was made impossible when the job advert placed by the Home Office and Metropolitan Police Authority stipulated that applicants must be British citizens.
The vacancy at the top of the UK's biggest police force was created by the resignation of commissioner Sir Paul Stephenson following the revelation of links between senior officers and the News of the World. Sir Paul's departure was swiftly followed by the resignation of assistant commissioner John Yates.
The Prime Minister last month raised the prospect of foreign police chiefs being recruited to "bring in fresh leadership". In a statement to MPs on the fallout from the News of the World hacking scandal, Mr Cameron asked: "Why shouldn't someone with a different skill set be able to join the police force in a senior role? Why shouldn't someone who has been a proven success overseas be able to help turn around a force at home?"
However Downing Street poured cold water on suggestions that Mr Cameron had approached Mr Bratton to take on the Met's top job. His proposals for foreigners to be made eligible for senior police posts was being considered by Tom Winsor's review of police pay and conditions, which had still to report, said a spokesman.
The Number 10 spokesman said: "Downing Street has not approached anyone to become chief constable of the Metropolitan Police. The PM and Home Secretary both agree that we should look at radical proposals for the future of leadership in the police service. That is what Tom Winsor, the Government's independent reviewer of police pay and conditions, is considering and will make recommendations on."
Sir Hugh Orde, the president of the Association of Chief Police Officers and himself a front runner for the commissioner's job, has been harshly critical of the idea of recruiting top police from overseas. He said: "The notion that you can ship someone in from another country to run a police force in a different environment and a different culture is quite simply stupid."
The Telegraph cited an unnamed Whitehall official as saying that Ms May had no problem with Mr Bratton personally, but was uncomfortable with the idea of ending the tradition of British citizens heading British police forces.
The Home Secretary has the power to appoint the new commissioner, after consulting with London mayor Boris Johnson. A Home Office spokesman said: "The Government is clear: we have the best police in the world and we will recruit the best person to become the next commissioner of the Metropolitan Police. The advertisement out on 21 July makes clear the criteria."