Afghan authorities have freed hundreds more Taliban prisoners, as calls grow for the militants to extend a ceasefire on its third and final day.

The historic pause in fighting - only the second in nearly 19 years of war - has mostly held across Afghanistan, providing a rare respite from the conflict's grinding violence.

Authorities said they planned to release about 900 Taliban prisoners across Afghanistan today, approximately 600 of them from the notorious Bagram jail near Kabul.

The release is part of a pledge by the Afghan government to free up to 2,000 insurgent prisoners in response to the Taliban's three-day ceasefire offer, which began Sunday to mark the Muslim holiday of Eid al-Fitr.

The prisoners had signed written pledges not to return to the battlefield, but Qari Mohammadullah, a freed inmate, vowed to continue fighting if foreign forces remain in Afghanistan.

"We don't want foreigners to stay any longer in our country, they must leave immediately," hesaid.

"We will continue our jihad until every single foreign force leaves."

Each freed inmate was given the equivalent of about $65 in Afghan currency.

The exact number of prisoners to be released Tuesday could vary subject to legal procedures, National Security Council spokesman Javid Faisal told AFP.

He said authorities hoped the Taliban would extend the ceasefire so delayed peace talks could commence.

"If the Taliban are ready to extend the ceasefire, we are ready to continue the ceasefire too," Faisal told a news conference.

"We hope they release our prisoners so that intra-Afghan peace talks begin as soon as possible... The future depends on the Taliban's next move," he said.

A senior Taliban member told AFP the group planned to release about 200 Afghan security force members, without specifying when.

The ceasefire has raised hopes of an extended truce that could pave the way for long-awaited peace talks between the Taliban and Afghan government.

"Extend the ceasefire. Save lives," Shaharzad Akbar, head of the Afghanistan Independent Human Rights Commission, said on Twitter.

"End the violence so that we can all focus on making services available to the most vulnerable across the country, on expanding access to human rights, so that we have space to breathe."

Another senior Taliban source told AFP the group could extend the ceasefire by seven days if the government speeds up the release of prisoners.

However insurgent spokesman Zabihullah Mujahid said he had no information about an extension.

The US-Taliban deal stipulates the Afghan government would release up to 5,000 Taliban prisoners and the militants would free about 1,000 national security personnel.

Prior to this week's releases, Kabul had already freed about 1,000 Taliban inmates, while the insurgents released about 300 Afghan security force captives.

US Secretary of State Mike Pompeo, while welcoming the latest developments, has insisted that freed Taliban prisoners should not return to the battlefield.

President Ashraf Ghani has said his administration is ready to begin peace negotiations - which had originally been scheduled to start by 10 March - seen as key to ending the war in the impoverished country.

Before the ceasefire started the Taliban claimed multiple deadly attacks against Afghan forces across the country.

But they denied carrying out a gruesome rampage in a maternity hospital in Kabul earlier this month when gunmen shot dead mothers, nurses and newborns.

The US first built the Bagram detention centre early in the war and it gained international notoriety after details emerged of prisoner abuse.

The Afghan military now runs the facility.

Trump renews desire to pull out of Afghanistan

Meanwhile US President Donald Trump has renewed his desire for a full military withdrawal from Afghanistan, but added that he had not set a target date.

It comes amid speculation that he might make ending America's longest war part of his re-election campaign.

"We're there 19 years and, yeah, I think that's enough... We can always go back if we want to," Mr Trump told a White House news conference.

Asked if the Thanksgiving holiday on 26 November was a target, Mr Trump said: "No. I have no target. But as soon as (is) reasonable. Over a period of time but as soon as reasonable."