Six militants and two troopers of the paramilitary Frontier Corps were exchanged in Shawal area of South Waziristan tribal region, the sources said.
The militants were then taken to neighbouring North Waziristan Agency, described by US and Afghan officials as a safe haven for Taliban and Al Qaeda elements.
There was no official word from the Pakistani military on the development, which came just two days after political parties endorsed Prime Minister Nawaz Sharif's plans to tackle a Taliban insurgency by holding talks with militants.
The Taliban are currently mulling the government's offer to hold talks.
Last year, the banned Tehrik-e-Taliban Pakistan offered talks to the previous Pakistan People's Party-led government. They withdrew the offer after their deputy leader Waliur Rehman was killed in a US drone strike.
The government has concluded several peace deals with Taliban factions in the past but all of them fell apart within months. Analysts have said the militants agreed to the deals only to gain time to regroup.
