The US signed a February 29 deal with the Taliban that set in motion the withdrawal of forces and called for the release of captives ahead of talks between the Islamist insurgents and the Kabul government.
But the internationally recognized government, which was already reluctant, has put off the release, saying Kabul needed time to review the identities of prisoners.
"The United States would like to see prisoner releases begin as soon as possible in line with the US-Taliban agreement," said Zalmay Khalilzad, the US negotiator who brokered the deal with the Taliban.
"Coronavirus makes prisoner releases urgent; time is of the essence," he wrote on Twitter.
He said that the global pandemic meant the two sides would likely need to hold talks virtually, although he still voiced hope for a face-to-face meeting. He had earlier called for the insurgents and government representatives to meet in Qatar, the site of a year of US-Taliban negotiations, to agree on the logistics of the prisoner swap.
Khalilzad said that the Taliban, who have not renounced violence against the government, have agreed to the key demand of the government that freed guerrillas not return to battle.
"The Taliban commit that released prisoners will abide by the commitments made in the peace agreement and not return to the battlefield. A violation will undermine the peace process," Khalilzad said.
The Taliban have demanded the release of 5,000 prisoners before meeting with the government for talks, which Norway had offered to hold starting March 10.
President Ashraf Ghani had agreed to release 1,500 captives with the remaining 3,500 to be freed as negotiations begin. But the Taliban rejected the offer and the government's release of prisoners did not begin as decreed on Saturday.
The Taliban under the agreement would free 1,000 captives. The United States is hoping to pull all of its troops out of Afghanistan and end its longest-ever war, which was launched after the September 11, 2001 attacks.

Copyright Agence France-Presse, 2020