Image caption Afghanistan's High Peace Council is in Islamabad for talks with the Pakistani government over Taliban releases

Pakistan has agreed to free several jailed Afghan Taliban officials during talks in Islamabad with Afghan peace negotiators, officials say.

But the Afghan delegation has extended its stay for an extra day, amid disagreements about who will be freed.

Afghan sources told the BBC the former Taliban justice minister Mullah Turabi and two intelligence officials are among the group who will be released.

One Afghan official described the move as a positive gesture towards peace.

Pakistan says it backs peace efforts. The BBC's Orla Guerin says the releases are a tangible step to prove this.

Our correspondent, reporting from Islamabad, says that the key issues are who is being freed, and how much power they have.

Crucially, it appears that the Taliban number two, Mullah Abdul Ghani Baradar is not among those being released - at least for now.

However, Afghan officials hope that Mullah Turabi can bring field commanders into talks. But one Taliban leader told the BBC he no longer has any influence over the movement.

Afghan politicians have given a mixed reaction to reports of the releases.

A senior official said the release of the Taliban detainees will help the push for a peace deal, but analysts caution it is the beginning of a long process.

'Positive gesture'

Analysis Since the Taliban pulled out of preliminary negotiations with the US in March, there has been little sign of movement in peace efforts in Afghanistan. At a minimum, Pakistan's decision to release several Taliban prisoners could generate some momentum. Islamabad has plenty of high-ranking Taliban to choose from. It is holding as many as 50 significant figures, according to one source, including shadow governors - part of a parallel Taliban power structure - and the Taliban number two, Mullah Baradar. But Pakistan appears unwilling to give him up yet. There is dispute about the relevance of some of those who are expected to be freed, including the former Taliban Justice Minister, Mullah Nooradin Turabi. An Afghan Taliban commander told the BBC that freeing him would make no difference, because he has no influence over the organisation.

They say that the releases are significant and the hope now is that when the Taliban officials return home, they can influence others to enter talks.

Afghan officials have long lobbied for the release of Taliban prisoners by Pakistan in the hope that direct contacts with top insurgent commanders could boost peace talks.

"We aren't too certain whether they can play an important role in peace negotiations but it is a positive gesture from Pakistan in helping peace efforts," an Afghan official told the Reuters news agency.

Officials say that it is not clear when the releases will occur and the details are still being worked out.

A political settlement between the Afghan government and the Taliban is widely seen by analysts as the most effective way of delivering stability to Afghanistan before most Nato troops withdraw at the end of 2014.

In March, the Taliban suspended preliminary peace negotiations with the US, saying that Washington's efforts to involve the Afghan authorities were a key stumbling block.

Correspondents say that Wednesday's announcement is a major achievement for Afghanistan's High Peace Council, which has been campaigning in Islamabad for Taliban releases and has been struggling to reduce mistrust between the Taliban and the government in Kabul.

The 70-member peace council was set up more than two years ago by Afghan President Hamid Karzai to open negotiations with insurgents.

It was given the task of reaching out to hundreds of Taliban field commanders, but it has consistently failed to woo any senior figures away from the insurgency.

In May, Arsala Rahmani, a key member of the council, was shot dead in Kabul in an attack blamed on the Taliban. Officials said it was a major blow to President Karzai.

In September 2011, the chief of the council, Burhanuddin Rabbani, was killed by a suicide bomber posing as a Taliban peace envoy.

Both Afghan and American officials have often accused Pakistan of backing insurgents - including the Haqqani group - as its proxies in Afghanistan to counter the influence of its rival India.

But Pakistan has rejected those claims.

Earlier this month, however, the UN Security Council's Taliban sanctions committee added the Haqqani group to its blacklist. The US state department designated the group as a terrorist organisation in September.