Foreign Secretary William Hague said today it would be "very surprising" if Afghan forces were not able to take responsibility for their country's security within the next four years.
While he insisted there was no set timetable for the withdrawal of British troops from Afghanistan, he said that the conditions for them to come home should be in place by the expected date of the next general election.
His comments came after Defence Secretary Liam Fox yesterday issued a sharp warning against any premature pull-out by international forces - saying it could jeopardise national security and would be a "betrayal" of those who had died fighting the Taliban.
The tone of Dr Fox's remarks contrasted sharply with those of David Cameron who said at the weekend that he hoped to bring back the British forces by the time of election, due to be held in 2015.
Mr Hague, however, insisted that there had been no contradiction in what they were saying.
"We are committed to the Afghans being able to conduct their military operations and security and that takes time. But I would be very surprised if that took longer than 2014," he told the BBC Radio 4 Today programme.
"Of course, in the next parliament he (Mr Cameron) would hope - anyone would hope - that the British combat troops were coming home. But he's also stressed that's not setting a timetable for what happens over the next few years.
"We have always said - the Chief of the Defence Staff has said - that the Afghan forces should be able to conduct their own affairs, should be able to stand up for themselves without other nations having to be alongside them, by 2014.
"So I don't think it's any great surprise or any great mystery about us saying that by 2015 really we should be in the position where Afghan national security forces will be looking after themselves."
In his first major speech since taking office, Mr Hague said that Afghanistan remained the coalition Government's "top foreign priority".
Setting out his vision for a "distinctive British foreign policy", Mr Hague reiterated his commitment to the "unbreakable alliance" with the United States, while at the same time stressing the need to build new ties with emerging nations like India and China.
"In recent years, Britain's approach to building relationships with new and emerging powers has been ad hoc and patchy, giving rise to the frequent complaint from such governments that British ministers only get in touch when a crisis arises or a crucial vote is needed," he said.
"This weakens our ability to forge agreement on difficult issues affecting the lives of millions around the world and overlooks the importance of consistency and personal relationships in the conduct of foreign policy."
In Europe he said that while Germany and France remained "crucial partners", Britain needed to look to other nations in order to "exert influence and generate creative new approaches to foreign policy challenges".
He also promised to build up UK influence in Brussels, promoting a new generation of British euro-crats to fill the "generation gap" which, he said, the previous Labour government had allowed to develop in some parts of the EU.
"It is mystifying to us that the previous government failed to give due weight to the exercise of British influence in the EU. They neglected to ensure that sufficient numbers of bright British officials entered EU institutions," he said.
"As a new Government, we are determined to put this right."
His criticisms of Labour were dismissed by shadow foreign secretary David Miliband.
"The idea of him lecturing the Labour Party about joined-up government, when the Defence Secretary and Prime Minister can't go more than two days without disagreeing about our most important foreign policy objective, is risible." he said.