The Afghan government has postponed its plan to release Taliban prisoners, a senior official said Saturday, throwing a precarious peace process between the insurgents and Kabul into deeper crisis.

President Ashraf Ghani earlier this week announced that the authorities would free 1,500 insurgents as a "gesture of goodwill" before negotiations begin, in an attempt to resolve one of the long-running disputes that had roiled talks.

The insurgents had earlier rejected the offer and demanded that up to 5,000 captives are released ahead of talks, citing the US-Taliban deal signed last month that excluded Kabul.

On Saturday Javid Faisal, spokesman for the National Security Council, told AFP that "the prisoners' release has been delayed" to allow more time to review their identities. "We have received the lists of the prisoners to be released. We are checking and verifying the lists, this will take time", he said.

Ghani's decree said the government would release 1,500 captives starting Saturday if the insurgents cut violence, with plans to free another 3,500 prisoners after negotiations begin. "We want guarantees that they will not return to fighting," Faisal said.

Since the US-Taliban agreement was signed in Doha on February 29, violence has flared up, with the insurgents carrying out dozens of attacks across the country, killing Afghan forces and civilians. There was no immediate reaction from the Taliban to the delay announcement, which is likely to further stall peace talks, which were originally expected to begin on March 10.

On Wednesday, the government warned it would resume offensive operations against the militants if violence continues, ending a unilateral partial truce put in place ahead of the talks. Political chaos in Kabul has complicated matters further, with Ghani's former chief executive Abdullah Abdullah also claiming the presidency following last September's election, which was marred by delays and allegations of voter fraud.

On Monday, Abdullah swore himself in as president minutes after Ghani took the oath of office. According to the Doha agreement, foreign forces will withdraw from the country within 14 months in exchange for Taliban security guarantees and a pledge to hold talks with Kabul.