The blast happened in a protected government administration compound during a meeting between government officials, local tribal leaders and groups opposed to the Taliban.
"There were two bombers. They were on foot," a local official said.
"The first blew himself up inside the office of one of my deputies while the second one set off explosives when guards caught him."
The attack happened in Ghalanai, the main town in the Mohmand Agency, one of the Federally Administered Tribal Areas. Ghalanai is around 110 miles from Islamabad.
The tribal area comprises the separate, semi-autonomous administrative units of seven agencies and six smaller frontier regions lying along the politically sensitive border with Afghanistan.
The mainly pastoral and exceptionally rugged FATAs, which have many trade routes over the mountains -- smuggling is widespread -- have a population of around 3.2 million, less than 3 percent of Pakistan's total population.
The Taliban and al-Qaida heavily influence the area, one of the poorest regions in the country.
The Pakistani army's offensive against extremist groups has displaced an estimated 2 million people in the FATA. Because the loosely administered area is close to Afghanistan, foreign governments, as well as that of Pakistan, strongly advise against traveling there.
At the end of last month, six people, including two small boys and one policeman, died in another suicide bomb blast in Bannu, a town within Khyber Pakhtunkhwa province, previously called the North-West Frontier province, directly south of the FATAs.
In that attack, a man was walking close to a police van, thought to be the target, when he detonated the device, local police said.
Extremist groups increasingly attack meetings between federal administrators and local leaders. Last July, another double suicide bombing in the village of Yakaghund in Mohmand Agency killed more than 100 people at a local meeting.
A recent report compiled by Pakistan's Federal Investigation Agency's Counter-Terrorism Wing said the death toll from this year's 37 suicide bomber attacks climbed to more than 640 and injured more than 1,800 people. Most of the people killed and injured in the suicide bombings were civilians but there have been several political leaders targeted.
Physical targets include government and security offices, personnel and public property, mosques, shrines and schools.
Of the 37 attacks, 25 took place in Khyber Pakhtunkhwa. Vehicles filled with explosives were used in 10 of the attacks.
For several years, the Pakistan government, supported by foreign aid donations, especially from the United States, has been working with tribal leaders in the FATAs to make accommodation with extremist groups less appealing.
A report in The New York Times in July 2007 said the United States was pouring millions of dollars of aid into the FATAs over the next five years as part of a "hearts-and-minds" campaign to win over the local population.
However, given the poor administration of the area, what happens to the money has been a major issue, the article said. How much aid money gets down to the grassroots level to improve the ordinary person's life is cause for concern.
"Delivering $150 million in aid to the tribal areas could very quickly make a few people rich and do almost nothing to provide opportunity and justice to the region," said Craig Cohen, author of a study of U.S.-Pakistan relations at the Center for Strategic and International Studies in Washington.