Afghan government and Taliban representatives said on Wednesday they had reached a preliminary deal to press on with peace talks, their first written agreement in 19 years of war.

The agreement lays out the way forward for further discussion but is considered a breakthrough because it will allow negotiators to move on to more substantive issues, including talks on a ceasefire.

"The procedure including its preamble of the negotiation has been finalised and from now on, the negotiation will begin on the agenda," Nader Nadery, a member of the Afghan government's negotiating team, told Reuters.

The Taliban spokesman confirmed the same on Twitter.