The Taliban vowed a prolonged war in Afghanistan if foreign troops stay after the end of 2014, as Kabul and Washington were preparing to discuss the "residual" US presence.

The Taliban vowed a prolonged war in Afghanistan if foreign troops stay after the end of 2014, as Kabul and Washington were preparing to discuss the "residual" US presence.

"If America wants to leave a small or large number of its troops for whatever length of time then it means war and destruction will continue in the region for that same length," the Taliban said in a statement.

"If Karzai and the Kabul regime agree with the presence of even a single American soldier then, just as presently, they shall also be responsible for all future hostilities, casualties and destruction."

The latest media reports suggest the US Department of Defense has prepared plans that leave either 3,000, 6,000 or 9,000 troops in the country.

US Defense Secretary Leon Panetta has said the slimmed-down force would focus on preventing Al-Qaeda from regaining a foothold in the Afghanistan.

The NATO coalition reduced troop numbers by about 30,000 in 2012 and is due to end its mission by the end of 2014.