Peace envoy Zalmay Khalilzad is leading the latest round of talks with the Taliban in Doha, where the two foes are pursuing a deal that would see the withdrawal of foreign forces from Afghanistan in return for Taliban security guarantees.

"All sides laying down arms is the outcome of any peace process," Khalilzad tweeted.

"All sides agreeing to reduce violence is a necessary step toward achieving that outcome and the morally responsible choice to make. We stand ready."

Khalilzad's comments come a day after Afghan President Ashraf Ghani said he was prepared to call an "immediate" and "permanent" ceasefire -- but the Taliban appeared to rebuff the offer.

Ghani had also offered to release 175 prisoners as a goodwill gesture. His talk of a ceasefire comes as momentum builds in various Afghan peace talks.

Thousands of tribal elders, women and representatives met last week at a massive "loya jirga" peace summit in Kabul, which ended with a demand for a ceasefire between government and Taliban forces.

The talks between the Taliban and the US, who have met about a half dozen times in recent months, are taking place separately in the Qatari capital Doha.

Neither Khalilzad or the Taliban have said much about progress in their latest talks, but Taliban spokesman Zabihullah Mujahid on Friday tweeted that America should "forget about the idea of us putting down our arms" and "stop repeating failed strategies & expecting different outcomes."

Last year, the Taliban announced a three-day ceasefire at the end of Ramadan after Ghani declared a unilateral truce for eight days earlier in the month.

It was first formal nationwide ceasefire since the US-led invasion of 2001 and saw unprecedented scenes of reconciliation and jubilation across the country.

Meanwhile, Afghanistan's war rages on, with thousands of civilians and fighters being killed each year.

US forces continue to train Afghan partners on the ground and strike the Taliban from the air, in a bid to push the war to a political settlement.