Afghan President, Ashraf Ghani, says his government has not pledged to free Taliban prisoners, as stated in a deal reached by the US and the militants.
Under the landmark agreement signed on Saturday in Qatar, 5,000 Taliban would be released in exchange for up to 1,000 government detainees by 10 March.
Mr Ghani said such a prisoner release “cannot be a prerequisite for talks”, but must be part of negotiations.
The US-Taliban agreement includes a phased withdrawal of US troops.
In return, the hard-line Islamist group agreed to hold peace talks with the Afghan government.
The deal also commits the Taliban to prevent al-Qaeda and all other extremist groups from operating in the areas they control.
The US invaded Afghanistan weeks after the September 2001 attacks in New York by al-Qaeda, then based in Afghanistan. The Taliban were ousted from power but became an insurgent force that by 2018 was active in more than two-thirds of the country.
Less than 24 hours after the deal was signed in Doha, the Afghan president told reporters in Kabul: “The reduction in violence will continue with a goal to reach a full ceasefire.”
But he added: “There is no commitment to releasing 5,000 prisoners.
“This is the right and the self-will of the people of Afghanistan. It could be included in the agenda of the intra-Afghan talks, but cannot be a prerequisite for talks.”
Any prisoner release, he added, was “not in the authority of the US” but “in the authority of the Afghan government”.
An estimated 10,000 captured Taliban are being held in Afghanistan.