The militants control swathes of Pakistan's tribal areas
The Pakistani Taleban have killed 22 tribesmen captured this week when they seized a town in the north-west.
Locals found the bodies by the roadside outside the town of Jandola in South Waziristan tribal region - some shot dead, others with their throats slit.
They belonged to a rival tribe considered by some to be friendly to the government, officials said.
The inter-tribal conflict follows a massive army operation against the Taleban in South Waziristan.
The government is now trying to end the violence through negotiations.
The BBC's Barbara Plett in Islamabad says such clashes could threaten the government's strategy of striking peace deals with the Taleban.
It could also stretch an army that is facing increased Taleban activity in other parts of the north-west, she says.
The negotiations have prompted protests from Nato and Afghan forces, who fear a strengthened Taleban insurgency across the border in Afghanistan.
The tribesmen were among at least 30 members of the Bhittani tribe who were kidnapped by fighters loyal to Taleban leader Baitullah Mehsud on Monday when they briefly overran Jandola.
Local officials and residents say the bodies were found dumped early on Wednesday.
Jandola is an important garrison town in South Waziristan, where the Taleban have a strong presence.
Clashes between the two groups - who have a long-standing feud - left at least 12 people dead on both sides, including eight militants, two women and two children.
The head of the Jandola administration, Barkatullah, told the BBC that 22 of the 30 Bhittani tribe members who were kidnapped had been killed by their captors.
"The villagers found their bullet-riddled bodies dumped in a ravine in Jandola region," he said.
Taleban militants had now pulled out of the town, fearing reprisal attacks by the military, he added.
The dead include fighters of the Niamatkhel branch of the Bhittani tribe that dominates Jandola tribal territory and the neighbouring Tank region of Pakistan's North West Frontier Province (NWFP).
BBC correspondents say the tribe has the backing of government forces, and has been challenging the influence of Baitullah Mehsud's fighters in the area.
Some observers say the Bhittanis co-operated with the army against the Mehsuds, and the Taleban attack on Jandola was in revenge.
But one security official said the trigger was more specific. He said the Bhittanis had been stopping Mehsud vehicles passing through their territory, and insisting that even the women be checked - a taboo in the deeply conservative tribal culture.
The army has a base in Jandola and moved troops into offensive positions during the fighting.
But the Mehsuds have since withdrawn and the incident is not expected to affect peace talks between them and the government, our correspondent says.
A joint jirga, or council, of the two tribes "is talking to both groups in order to prevent further escalation", Mr Barkatullah said.
Meanwhile, security forces continue to block the main road connecting the region with the rest of the country, officials and witnesses say.
The road was closed to traffic on Tuesday in the wake of Jandola's fall to pro-Mehsud militants.
The move is meant to put pressure on the Baitullah Mehsud group and to keep the field clear for an operation if hostilities escalate, security officials said.