Karzai said he was weighing up concerns that managing big changes in leadership and security at the same time could be too heavy a strain on his country, after a decade with him in charge and foreign troops on the ground.

“I have been talking about this for some time now, and this is quite a good consideration, [whether] we cannot have all of that accomplished in 2014 because of the heavy agenda,” Karzai told a news conference in Kabul, held with the visiting Nato secretary general, Anders Fogh Rasmussen.

“Should we allow the transition process to complete itself in 2014, but bring the presidential election one year earlier to 2013?” he said.

He also raised the possibility of bringing the security handover forward. Earlier this year he called for a speeded-up transition schedule.