The blast destroyed the restaurant in the town of Jandola
At least 10 people have been killed in a suicide bombing in north-western Pakistan, local officials say.
About 20 people were also reported to have been injured in the explosion at a restaurant in the town of Jandola in South Waziristan.
Officials said a group of militants opposed to Pakistan's top Taleban commander had been in the restaurant.
Violence in Pakistan has surged in recent months amid a wave of attacks blamed on Islamist militants.
Some of the injured were reported to be in a critical condition and officials said the number of dead could rise.
The BBC's Syed Shoaib Hasan in Islamabad says the bomber walked into the restaurant on Thursday morning and blew himself up, destroying the premises.
The attack targeted Turkistan Bittani, a pro-government tribal leader who is a rival of local Taleban warlord Baitullah Mehsud.
Turkistan Bittani, who has been helping the military take on Mehsud, had left the restaurant minutes before the attack.
Turkistan Bittani leads one of the "peace committees", or pro-government armed militias, that oppose the Taleban.
The South Waziristan region is dominated by Mehsud.
Our correspondent says Mehsud is one of the most wanted Taleban militants operating on the Pakistan-Afghanistan border.
He is suspected of masterminding dozens of suicide attacks across Pakistan as well as attacks on Nato forces in Afghanistan.
The latest attack comes a day after a suspected US missile strike in South Waziristan killed seven Arab militants.
It also follows an announcement on Wednesday by the US state department of a $5m bounty for information leading to the capture of Mehsud.
Mehsud has also been accused of plotting the 2007 assassination of former Prime Minister Benazir Bhutto.
Since 9/11 Mehsud has grown in strength and stature and is said to command about 20,000 pro-Taleban militants. A majority belong to the Mehsud tribe.