By Mohammed Abbas
CAMP BASTION, Afghanistan (Reuters) - - Britain will decide at the end of this year how many of its troops will leave Afghanistan in 2013, Prime Minister David Cameron said on Wednesday after arriving in Afghanistan on an unannounced visit.
Britain is due to withdraw 500 soldiers by the end of this year, but Cameron would not say how many would be repatriated next year, adding only that he was confident the shift of security duties from British to Afghan forces was going well.
"I don't want to get into numbers now, I don't want to raise false hopes. There's a modest reduction this year, there will be further reductions next year to be announced at the end of the year, all based on the conditions on the ground and how transition is going," Cameron told reporters.
"What I'm getting is, transition is working," he said, referring to the message he had received after speaking to British military chiefs in southern Afghanistan.
Britain has some 9,500 troops in Afghanistan, the second largest foreign force in the country after the United States, and plans to withdraw the bulk of its soldiers by the end of 2014.
More than 400 British troops have been killed in Afghanistan since the U.S.-led invasion in 2001, a statistic that along with Britain's strained finances has added to pressure to end its military involvement in Afghanistan.
Cameron, whose government is overseeing a substantial cut in Britain's military post-2014 in response to economic pressures, has said in the past that he did not want a "cliff edge" in two years when all remaining troops must leave Afghanistan at once.
A senior British military source dampened prospects of a large troop withdrawal soon, saying Britain planned a "glide path" down in force strength.
"If the prime minister's aims don't change, and that is to maintain a viable state with an ANSF (Afghan National Security Force) that can protect its borders and counter terrorism, then we need to maintain a strong presence," the source said.
Afghanistan's prospects after foreign forces leave are uncertain, with corruption widespread and the country currently experiencing some of the worst violence since the Taliban government was toppled more than a decade ago.
Adding to worries are presidential elections due in 2014 - the same year as the NATO-led coalition phase-down - at which President Hamid Karzai must step down.
In its latest progress report on Afghanistan, Britain said violence in June was higher than in the same period last year due to an early end to the poppy harvest, used in the manufacture of heroin, allowing insurgents to fight earlier.
British troops have mainly been based in Helmand province in Afghanistan's southwest, which has seen some of the bloodiest fighting in the Afghan conflict, but British military sources say there is now a degree of stability.
But combating the corruption that hinders economic development and Afghan military supply lines will be key to maintaining stability once foreign forces depart, they said.
Major donors pledged this month to give Afghanistan $16 billion in development aid through 2015, but demanded reforms to fight corruption.
(Editing by Rob Taylor and Alison Williams)