The bomber blew himself up as hundreds of people were gathered around the office of a senior government official in Yakaghund town in Pakistan's northwestern Mohmand region, where security forces have stepped up attacks on Taleban militants in recent weeks.
The attacker apparently targeted tribal elders who had come to the office of Rasool Khan, assistant political agent of Mohmand, for a meeting.
"Now the death toll is 65. Around 112 people have been wounded," Khan said.
Among the wounded were several people displaced by fighting between security forces and militants, who were collecting relief goods near the blast site. Residents said five children, aged between 5 and 10, and several women were among the dead.
"I was standing about 200 yards away from the office when I heard the blast. I don't know how it happened but I could see several bodies lying on the ground after the explosion and people running in all directions," said Riaz Hussain, a witness.
Television footage showed victims being pulled from the debris. The blast also damaged several cars and about 30 shops, witnesses said.
A security official at the scene said the blast also damaged a nearby prison wall and several inmates escaped.
Pakistan launched two major offensives in the northwest last year against homegrown Taleban militants who have killed hundreds of people in retaliatory attacks across the country, mostly in the northwest, but also in major cities.
Two suicide bombers killed at least 42 people in an attack on a religious site in the eastern city of Lahore last week.
The Pakistani Taleban, allies of the Afghan Taleban, have lost ground in army offensives over the past year. They were pushed out of the Swat Valley, northwest of Islamabad, and in October the army began an offensive in the militants' South Waziristan bastion on the Afghan border.
The offensive was extended to Orakzai in March as many of the militants who fled the South Waziristan operation took refuge there and in Mohmand. Hundreds of militants have since been killed in airstrikes in the two regions.
Warplanes killed about a dozen militants in attacks in Orakzai on Friday, security officials said. There was no independent verification of the casualties as militants often dispute and reject official figures.
In South Waziristan, suspected militants kidnapped two engineers working on a water project in the region, officials said.
