Sir John Stevens

Britain's top police officer has expressed concern at Conservative plans to introduce US-style elected sheriffs.

Sir John Stevens, head of London's Metropolitan Police, warned that they could lead to a more politicised police service.

The Conservatives launched the plans at this autumn's party conference, vowing to "trust the people" and end central interference in local policing.

Under the plans, an elected sheriff could take overall responsibility for the local policing strategy. More power could also go to the local mayor or police authority in a bid to bring policing closer to local community priorities.

Chief constables would report to the local politicians, but would also be guaranteed operational independence through new legislation.

But Sir John warned against introducing aspects of American policing into the UK.

"I have seen a lot of what happens in America. I think the strength of British policing is to be apolitical, so that we are not influenced by politicians," he told BBC1's Breakfast With Frost programme.

"It is absolutely essential and it is the golden thread of British policing. We are apolitical, we are independent. We must ensure that continues."

But Sir John added that he had "no problem" with local accountability. "We are looking for a step change in London to drive down accountability to ward level, linking in with local councillors and the like," he said.