PESHAWAR, Pakistan - A suicide bomber hit a Pakistani mosque during Friday prayers, killing at least 43 people and wounding more than 100 others in the tribal district of Khyber, officials said.

It was the deadliest attack for three months in the nuclear-armed Muslim country awash with violence blamed on Taliban and al-Qaida-linked networks where US special forces killed Osama bin Laden on May 2.

The explosion came as a US drone strike targeting militants in a house further south in the northwestern tribal belt killed at least four, according to local security officials.

The Khyber bomb exploded after more than 500 people had packed into the mosque in the town of Jamrud, 25 kilometers from Peshawar, the main city in the northwest where most of the violence in Pakistan is concentrated.

Senior administration official Sayed Ahmed Jan said that the bomb had exploded seconds after the main prayer ended.

The deputy chief of the Khyber tribal district administration said 43 people had been killed and 117 wounded.

"It was a suicide attack. The bomber was wearing about 8 to 10 kg of explosives and was on foot. He detonated in the main prayer hall," said Khalid Mumtaz Kundi.

Top administration official Mutahar Zeb said the wounded had been taken to nearby hospitals while a bomb disposal squad was at the scene.

Local television channels showed prayer caps and clothes soaked in blood on the ground at the scene, while the mosque's interior appeared badly damaged.

Like the rest of the Muslim world, Pakistan is observing the holy month of Ramadan in which faithful fast from dawn to dusk.

Iftikhar Khan, an official at the Hayatabad Medical Complex in Peshawar, said that 40 wounded people had been rushed there.

There was no immediate claim of responsibility for the attack but bombings blamed on Taliban and al-Qaida-linked networks have killed more than 4,550 people since 2007, destabilizing the nuclear-armed state.

Friday"s bomb was the deadliest since May 13 when two suicide bombers blew themselves up outside a police training center in a town about 30 km north of Peshawar, killing 98 people.

Meanwhile, a US drone fired two missiles, hitting a house in the Shin Warsak area of South Waziristan, part of the notorious tribal badlands that Washington calls the global headquarters of al-Qaida, the Pakistani officials said.

"Two missiles were fired at the house of a tribal elder where local militants were present," one security official said on condition of anonymity as he is not authorized to speak to media.

"Four dead bodies have been recovered and two are injured," the official added.

Shin Warsak is 15 km west of Wana, the main town of the district of South Waziristan, considered a militant stronghold.

The security official said initial reports suggested that a group of local militants linked to Taliban commander Mullah Nazir were present in the house at the time of the attack.

Two other Pakistani intelligence officials confirmed the drone strike and death toll.

The attacks come as Pakistan's biggest city, Karachi, is undergoing a fresh wave of ethnic, criminal and politically linked unrest that has left at least 52 people dead in the past 48 hours.

Agence France-Presse