The Pakistan government and Taliban militants in the restive South Waziristan tribal region are expected to swap prisoners as part of efforts for a formal peace agreement. Thirty-one militants have been airlifted from a prison in Dera Ismail Khan and detention centres in Wana, the main town of South Waziristan, and brought to Jandola, sources said. South Waziristan, dominated by the Mehsud tribe, is the base for Pakistani Taliban commander Baitullah Mehsud.

There were reports that Mehsud would oblige tribal interlocutors by freeing some security personnel and government functionaries being held by the militants. Taliban spokesman Maulvi Omar has claimed in the past that the Tehrik-e-Taliban Pakistan has 80 to 90 security personnel and government officials in its custody. A verbal agreement has been reached by the government and the militants, but it has not been made public, due to the 'sensitivities involved', the Dawn newspaper reported on Wednesday.

"I think a verbal agreement is there already. It has to be formalised but it is not being made public for obvious reasons," a source said.

A formal agreement could be reached in three to four days. The swapping of prisoners is expected to take place at Tiarza in South Waziristan, sources said. Six of the militants, who are set to be freed, were being held in the Dera Ismail Khan prison, 19 in the army's brigade headquarters at Zari Noor and two in detention centres in Jandola, sources said.

An official said all of them were members of the Mehsud tribe.

The military's chief spokesman denied that an army helicopter had been used to airlift the detainees. He also said the military was not involved in any prisoner exchange. "What is happening is that locals who may have been detained on suspicion without any strong evidence are being considered for release by the political authorities or Federally Administered Tribal Areas' administration. But the military is not involved," Major General Athar Abbas said.

Official sources also said that the military had started 'thinning down' its presence at Kotkai and Spinkay Raghzay in the Mehsud-dominated part of South Waziristan. "This is a good development and there may be some more good news," an official said.

Major General Abbas said that a decision on pulling out troops from South Waziristan would be made by the government and would depend on the outcome of negotiations with the tribes.

He acknowledged that the military had decided to readjust its current positions and reopen various roads linking villages and townships to facilitate the return of people who had been displaced by fighting in the region.

Pakistan's new coalition government has initiated steps, for holding peace talks with all militant groups that give up violence, shortly after coming to power in March. Prime Minister Yousuf Raza Gilani has said this is part of a new policy to tackle militancy, which combines political dialogue, socio-economic development and the military option.