ISLAMABAD, Pakistan - A pair of suicide bombers attacked a large gathering of anti-Taliban elders inside a government compound in northwest Pakistan on Monday, killing up to 50 people in one of the worst terror strikes in the volatile tribal belt this year.

The attack, which wounded about 100, occurred in the town of Ghalanai at the administrative headquarters of Mohmand, a region along the Afghan border that continues to see periodic clashes between Taliban extremists and Pakistani troops. A meeting was under way at the compound between leaders of a local anti-Taliban militia and a top Mohmand official, authorities said.

Witnesses said more than 300 people were inside the building when the two attackers appeared. One of the bombers was dressed in a police uniform and was able to walk into the offices where the crowd had gathered. A second bomber was stopped at a perimeter security gate. Both men detonated their explosives seconds apart.

Officials in Mohmand said that the compound had metal detectors at its entrance but that they were not functioning at the time because of a power outage.

Pakistani television showed sections of the compound in rubble and a long line of wounded people in bloodied tunics being rushed on stretchers into a hospital in Peshawar, northwest Pakistan's largest city.

Anti-Taliban tribal meetings and pro-government tribal militias have been frequent targets of insurgents in recent years. On Jan. 1, a man driving a pickup filled with explosives set off a blast near the town of Lakki Marwat, where members of an anti-Taliban tribal militia were playing volleyball. At least 75 people were killed.

In July, two suicide-bomb blasts tore through a busy market in the village of Yaka Ghund in Mohmand, killing at least 65 people in an attack that authorities said appeared to be aimed at members of a local anti-Taliban militia who had been meeting in the area.

Mohmand is one of several tribal regions along the Afghan border where Taliban and al-Qaeda extremists maintain hideouts. The Pakistani military has launched offensives in several parts of northwest Pakistan, in hopes of ending the wave of Taliban-engineered suicide bombings and other attacks that have ravaged the country in recent years.

Despite the offensives, the insurgency's top leaders remain active. Many extremists were able to flee the military operations in advance and find sanctuary elsewhere in the tribal belt.

The border between Afghanistan and Mohmand, as well as other regions in Pakistan's semiautonomous tribal belt, are poorly guarded and extremely porous, making it easy for extremists to escape and return. Main Iftikhar Hussain, information minister of northwest Pakistan's Khyber-Pakhtunkhwa province, said regional extremists could be defeated only if Pakistan better coordinated its counterterrorism efforts with U.S. and Afghan forces battling insurgents on the Afghan side of the border.

"Otherwise, we will keep suffering," he said. "There are predictions that this wave of terrorism may continue for the next 14 years."