Australia's defence chief on Tuesday said he hoped troops could hand over to Afghan forces in "three to four years," but warned pulling out too early would cause civil war, AFP reported.
Air Chief Marshal Angus Houston said a premature withdrawal of international forces would almost certainly deliver the troubled central Asian nation to the Taliban and result in a surge in global terrorism.
"If we were to all withdraw now we would leave the country in a situation where I think there would be a civil war, and there is a very strong possibility the Taliban would prevail," said Houston, delivering an update to press here on Afghanistan.
"If the Taliban were to prevail we would be likely to go back to the circumstances that we had before 2001, where the Taliban hosted groups like Al-Qaeda."
Houston's comments came as the body of young private, killed by a roadside bomb in Afghanistan Saturday, began its journey home. He was the 11th Australian soldier to die in Afghanistan since the conflict began in 2001.
Houston said troops were about "one third" of the way through a programme to mentor and train the Afghan National Army, and for the first time offered an estimate of a timetable for handing over responsibility for security in Uruzgan province, in the country's restive south.
"I would hope that over a period of time we will be in a position (to hand over) and I would hope it's three to four years," he said.
"But as we saw in Iraq there is more to it than just saying drawing a line and saying this battalion will be ready at this time," he added.
Australia has about 1,550 troops stationed in the country, mostly in Uruzgan, and Houston said "major attacks effected in western countries" would likely follow any hasty withdrawal.
Prime Minister Kevin Rudd echoed Houston's remarks, warning that terrorists in southeast Asia, "in the past responsible for bombings which have killed Australians, have been trained in Afghanistan."
"Afghanistan used to be an unrestrained training ground for terrorists who operate worldwide, including in southeast Asia," Rudd said.
"Our mission, together with our friends and allies around the world, is to prevent that from happening again."
Rudd in April committed 450 more soldiers to the conflict in Afghanistan, saying the current military strategy was failing and security was deteriorating.
Houston also promised a new, more open approach to publishing Afghan casualties, 80 percent of which he blamed on the Taliban.
"The Taliban are increasingly using allegations of civilian casualties to damage our reputation, reduce local support, weaken our resolve, tie up our resources and add to the complexity of the operational environment," he said.
"It is vital that in the event of an alleged or actual civilian casualty there are transparent, consistent and robust processes in place."