Afghan authorities have started to release 400 Taliban prisoners, the final hurdle in launching long-delayed peace talks between the two warring sides.

A group of 80 prisoners were released on Thursday, said Office of the Afghan National Security Council Spokesman Javid Faisal, tweeting that it would "speed up efforts for direct talks and a lasting, nationwide ceasefire."

Their release was approved at the weekend by a gathering of thousands of prominent Afghans called by President Ashraf Ghani after the authorities initially refused to free the militants, accused of serious crimes including brutal attacks that killed Afghans and foreigners.

Read more: Afghanistan to free 400 Taliban prisoners, paving way for peace talks

Both sides have said they are ready to begin talks in Doha, Qatar, within days of the prisoners being freed.

The prisoners include some 44 insurgents of particular concern to the U.S. and other countries for their role in high-profile attacks.

A peace deal signed between the United States and the Taliban in Qatar in February required the Afghan government to free 5,000 Taliban inmates in exchange for the Taliban's release of 1,000 soldiers or government staff.

Under the agreement, U.S. and NATO-led coalition forces would leave Afghanistan by July next year depending on whether the Taliban outfit meets the conditions envisaged in the agreement, including severing ties with foreign terrorist groups. 

Since early March, the Afghan government had previously released 5,100, including 500 prisoners who were not included in a Taliban list of prisoners, and the Taliban freed 1,000 Afghan soldiers or government staff, but the Afghan government suspended the release of 400 Taliban inmates over their involvement in serious crimes.

(With input from agencies)