Troops to stay in Afghanistan until 2014 says minister
The government has restated a target of removing UK troops from Afghanistan by 2014.
Leaked documents to a Sunday newspaper suggested a timetable for a phased transition to Afghan forces could begin within months.
But Defence Secretary Dr Liam Fox said 2014 remained the target for the handover of security control to Afghan forces.
Earlier, it was revealed that aid to the country is to be increased by 40%.
During and interview on the Andrew Marr Show, the defence secretary refused to comment on the Independent on Sunday's report on an accelerated timetable for troop withdrawals.
"It has always been our aim to be successful in the mission, and the mission has always said that the Afghan national security forces would be able to deal with their own security by 2014," he said.
Blueprint for withdrawal
But he said only combat troops would be expected to be withdrawn at that time, with a continued presence likely for training.
Mr Cameron's aim of 2015 was "quite conservative by comparison", he said.
Dr Fox went on: "As you would expect I would not comment on any leaked document but a leaked draft document for a potential communique of a conference that hasn't yet happened is, I think, quite a leak."
It has been reported that Afghan President Hamid Karzai will use a forthcoming international conference to publish a blueprint for the withdrawal of international troops by 2014.
Meanwhile, International Development Secretary Andrew Mitchell outlined plans to increase spending on aid projects in Afghanistan by 40%.
He told the Politics Show the government had been looking "very carefully" at the way money was being spent in Afghanistan.
"We've found some additional funding from less good programmes, so in principle we have an additional 40% money going into the development budget," he said.
It is believed the money for Afghanistan would be used to stabilise the most insecure areas, with more policing, emergency food and medicine, and thousands of job and training opportunities.
Shadow International Development Secretary Douglas Alexander called on the minister to clarify exactly how the aid money would be spent.
He said: "Thanks to the efforts of the last government, the UK was already the second-largest donor to Afghanistan and Helmand is already amongst the most heavily aided regions on earth.
"The primary challenge in those areas affected by the insurgency has not been a lack of money but a lack of security."
BBC deputy political editor James Landale said the government is "using foreign aid, not just to help people around the world but also to further British foreign policy".
"That's quite a change. It's also an answer, perhaps, to MPs who ask why aid budgets are being protected when so many others are being cut," said our correspondent.
The UK death toll in Afghanistan since operations began in 2001 now stands at 322, with four British serviceman dying since Friday.
At least three people were killed on Sunday by a suicide bomber in the Afghan capital Kabul.
The bombing came despite heightened security across Kabul ahead of the international conference of foreign ministers on Tuesday.
Foreign Secretary William Hague, US Secretary of State Hillary Clinton and UN Secretary General Ban Ki-Moon are among those scheduled to attend.