Germany is poised to reduce significantly the number of troops it contributes to the NATO-led force in Afghanistan next year, according to a report published on Sunday in Der Spiegel newsweekly.

The current upper limit of 4,900 troops will be slashed to "comfortably under 4,000" when the German government asks parliament in January for a new mandate for the force, Spiegel said.

It said Foreign Minister Guido Westerwelle and Defence Minister Thomas De Maiziere had also agreed to ask parliament for a mandate of more than the usual 12 months, so troops could be in place for elections due at the start of 2014.

The defence ministry declined to comment on the report saying the size and duration of the mandate had not yet been decided.

Germany is the third largest force under NATO's International Security Assistance Force, behind Britain's around 9,500 troops and the more than 90,000 US troops.

It has a maximum of 4,900 soldiers in Afghanistan but another 500 are set to be withdrawn by the end of this year before a complete pullout.

Foreign troops have now begun pulling out and all combat forces will be gone by the end of 2014, according to a withdrawal schedule agreed by the US and NATO.