LONDON (Reuters) - British troops will stay in Afghanistan for “as long as it takes,” the new head of the British armed forces said in an interview published on Monday, suggesting 1,000 British trainers could stay beyond 2015.

Prime Minister David Cameron has said Britain, which has the second-biggest foreign troop contingent in Afghanistan after the United States, could start withdrawing its troops as early as next year.

Cameron has also said Britain wants to pull the bulk of its 9,500-strong force out of the war zone within five years, in line with an international aspiration to give Afghans full control of their security by the end of 2014.

Gen. David Richards, who became Britain’s chief of the defense staff late last month, appeared to play down the prospect of any troop withdrawals in 2011 in an interview with The Sun newspaper.

“We are in a demanding part of Afghanistan and therefore, inevitably, we’re going to be shouldering the burden at least through next year,” he was quoted as saying.

“We really mean it when we say we will be there for as long as it takes. It’s so important that we establish in the minds of the Afghan people and of those in the region that NATO is not going to cut and run in Afghanistan,” he said.

He said British troops would be in a supporting role after 2015, but suggested that 1,000 British soldiers could stay on to help train Afghan security forces.

“The worst of all things would be to get out before we finish the job properly, for want of 1,000 trainers to keep them going for another couple of years,” he said, describing the war as “definitely winnable.”

British troops have been engaged in fierce fighting with Taliban insurgents in the southern province of Helmand: 342 British soldiers have been killed since 2001.

U.S. President Barack Obama, who last year ordered another 30,000 troops to Afghanistan, hopes to start bringing soldiers home from July 2011.

Critics say Obama’s strategy has backfired, sending a signal to the Taliban that the United States is preparing to wind down when U.S. and NATO forces are suffering heavy casualties.

A U.S. review of the Afghan war next month is expected to say Washington’s strategy is working despite increased violence and record casualties, and that the July 2011 deadline can be met.

Afghanistan will top the agenda at a NATO summit in Lisbon on November 19 and 20.