The Afghan government said Thursday it had released 400 Taliban prisoners under an exchange deal with the militants, except for "a few" opposed by foreign nations, and expected peace negotiations to start soon.

The two warring sides have grown closer this week to launching direct talks in Qatar, wrapping up a contentious and months-long prisoner exchange.

Kabul has already sent a logistical team to Doha where the Taliban's political office is based, with the negotiators expected to depart soon.

"The Islamic Republic of Afghanistan has received our commandos held hostage by Taliban, after which the Gov't released the remaining 400 convicts, except the few for which our partners have reservations," National Security Council spokesman Javid Faisal said on Twitter.

"Diplomatic efforts are ongoing. We expect direct talks to start promptly."

Two Taliban officials confirmed the prisoners had been freed but that those opposed by France and Australia were still in government custody.

Paris and Canberra objected to the release of the militants because of their links to the murders of French and Australian civilians and troops in Afghanistan.

"Australia and France have some considerations about them," one Taliban official told AFP on condition of anonymity.

"The Kabul administration will send them to Qatar where they will be in custody during the intra-Afghan talks."

A Western diplomatic source, however, said Kabul had still not taken a decision.

A date for the resumption of talks has not yet been set.

- Talks on horizon -

Negotiations were initially supposed to begin in March as agreed in a deal between the Taliban and Washington in February, from which Kabul had been excluded.

But repeated squabbles over the prisoner exchange delayed the negotiations, including the Taliban's demand that 400 prisoners accused of serious crimes be among those freed.

The prisoner swap agreed between the US and the Taliban stipulated that Kabul should release a total of 5,000 militants in return for the insurgents freeing 1,000 Afghan troops.

The Taliban have said they are willing to begin negotiations "within a week" of the exchange being completed and blamed Kabul for delaying the negotiations.

President Ashraf Ghani said on Wednesday that a "critical stage of peace" had been reached and that the talks would help reduce violence and finalise a permanent ceasefire.

On Thursday, Najia Anwari, spokeswoman for the State Ministry for Peace Affairs, said the government had "removed all the obstacles for the direct talks to start".

"The negotiation team of the Islamic republic is now in full preparation to attend the talks," she said.

Fraidoon Khwazoon, spokesman for Afghanistan's High Council for National Reconciliation, which is leading the overall peace process, said they would leave Thursday. 

But late in the day, two government officials told AFP that the Kabul-backed team had still not left for Doha.