Washington was attempting to speed up the process, which included pushing for the summit in Turkey that was to be attended by over 20 countries and global bodies.

 

UN spokesman Stephane Dujarric said on Tuesday that he could not confirm if the conference had been postponed.

 

"The United Nations, along with the co-conveners, Qatar, Turkey, we're continuing to engage with representatives of both the Islamic Republic of Afghanistan and the Taliban on ways to strengthen and add impetus to the intra-Afghan negotiations," Mr Dujarric told reporters.

 

The UN special envoy for Afghanistan, Deborah Lyons, was in Doha last week to discuss with Afghan parties "the best way the international community can support them in making progress on their negotiations towards a just and durable political settlement," Mr Dujarric said.

 

"Our focus will continue to be on progress in intra-Afghan negotiations, which is a critical part of the way forward."

 

A leading US general voiced "grave doubts" on Tuesday about the Taliban's reliability as a negotiating partner for Washington and Afghan diplomats in the event of the military's full withdrawal from America's longest war.

 

The Islamist Taliban ruled Afghanistan from 1996 to 2001, when they were ousted by US-led forces. Since then, they have waged a long-running insurgency and still control wide swathes of territory.