Conservative leader David Cameron appealed on Thursday for the return of his bicycle after a thief stole it from outside a supermarket in west London.

Cameron, who regularly rode the bike to the House of Commons, had chained it to a bollard while he popped into a Tesco store in Portobello Road to buy some groceries on Wednesday evening.

"Someone must have just picked it up and walked off with it," he told reporters.

"If anyone has seen this bicycle I would like it back."

He said he had reported the theft on Scotland Yard's online crime reporting site, but said he was pessimistic about its return. "I am not holding my breath."

Nearly 19,000 bicycles were reported stolen in London last year.

In March, Cameron pledged to cycle more carefully after the Daily Mirror newspaper filmed him riding through two red lights and the wrong way down a one-way street en route to the Commons.