NATO Secretary General Jens Stoltenberg on Thursday urged the Taliban to honour commitments to reduce violence and cut ties to terror groups, as the alliance weighs withdrawal from Afghanistan.  

Defence ministers from the Washington-backed allies are to discuss whether NATO's 10,000-strong mission should stay or go later this month. 

Former US president Donald Trump struck a deal with the Taliban last year under which the United States agreed foreign troops would leave Afghanistan by May 2021 if violence went down and peace talks with the Kabul government advanced.

New President Joe Biden's administration says it is reviewing that deal, but the Pentagon has accused the Afghan insurgent group of not meeting the promises they made.

"My message to the Taliban is that they have to live up to their commitments, especially when it comes to breaking all ties with international terrorists including Al-Qaeda and we need to see reduced violence," Stoltenberg told journalists.  

"We have seen attacks also against individuals, journalists and others, and of course the high level of violence is something that is of great concern." 

The Taliban has accused the US of breaching the peace deal and on Monday insisted it will continue its "fight and jihad" if foreign troops do not leave by May.

Trump in his final days in office unilaterally reduced US forces in Afghanistan to just 2,500 -- the lowest since the start of the war in 2001. 

Stoltenberg has repeatedly insisted that NATO members must decide "together" on the future of their mission and he hopes Biden will coordinate more closely with allies.

"If we decide to leave we risk to jeopardise the peace process, we risk to lose the gains we have made in the fight against international terrorism over the last years," the NATO chief said Thursday. 

"If we decide to stay we risk to continue to be in a difficult military operation in Afghanistan and we risk increased violence also against NATO troops."