PESHAWAR - A bomb exploded on a truck at a fuel station in northwestern Pakistan on Monday, killing seven people, police said, while the Taliban claimed responsibility for two weekend suicide attacks in a valley recently retaken by the army.
Gunmen also assassinated the leader of a feared Sunni sectarian group, triggering rioting in three southern cities.
Pakistan is battling al Qaeda and Taliban militants seeking to topple its secular, pro-Western government. It has been bracing for possible revenge attacks following the reported death of Pakistani Taliban leader Baitullah Mehsud in a U.S. missile strike.
Officials said late Monday they had arrested a key aide to Mehsud at a hospital in the capital, Islamabad.
Three children were among the dead in Monday's truck bombing, which wounded at least 15. Television footage showed bloodstained clothes and sandals scattered around the station in Charsada district, about 20 kilometres outside the main northwestern city of Peshawar, a militant hub with roads that lead into Mehsud territory.
Police officer Sifwat Ghayur said a timed explosive device fashioned from a mortar had been loaded onto the truck in a package marked "medicine" without the driver's knowledge.
The truck functioned as a taxi service between towns. Six of the dead were believed to have been passengers.
Also in the northwest, a Taliban spokesman in the Swat Valley said the group was responsible for two suicide bombings on the police and the army over the weekend that killed seven security forces.
"It is a reaction to the killings of our men in army custody," Muslim Khan told The Associated Press by phone. Residents reported finding 18 bodies -- most identified as Taliban -- in different areas of Swat on Saturday.
An army spokesman Saturday denied any government involvement in the killings, saying residents may have taken revenge for the Taliban's harsh, monthslong rule in the valley.
The Taliban spokesman also said the attacks were timed to coincide with the visit of U.S. envoy Richard Holbrooke, who had been scheduled to travel to Swat over the weekend but cancelled, citing heavy rain.
Holbrooke met Monday with Pakistani Prime Minister Yousuf Raza Gilani and praised the army's success in Swat and the adjacent Malakand region. The offensive, which began in April after the Taliban advanced to within 100 kilometres of the capital, Islamabad, was the military's largest anti-militant operation after years of intermittent peace deals.
The Pakistani Taliban were dealt a blow with the reported death Aug. 5 of top leader Mehsud in a CIA missile strike fired by an unmanned drone close to the northwestern border with Afghanistan.
On Monday, police said they arrested a close aide to Mehsud who was being treated in a private hospital in Islamabad.
Militant commander Qari Saifullah, who also has links to al Qaeda terrorists, told police he had been wounded in an American missile strike in South Waziristan, said two police officials, who spoke on condition of anonymity because they were not authorized to release the information. It was unclear if it was the same strike believed to have killed Mehsud.
Pakistan also suffers periodic spasms of violence between its Sunni and Shiite Muslim sects. In the southern commercial capital of Karachi, supporters of banned Sunni sectarian group Sipah-e-Sahaba rioted after its leader, Ali Sheer Haideri, was gunned down in his car Monday morning about 350 kilometres northeast of Karachi.
Haideri's group has been blamed for attacks against the country's minority Shiites, whom they regard as heretics. The U.S. State Department designated the group a terrorist organization in 2003.
Angered at his death, dozens of Sunni youths torched a bus and a van, according to Abdul Majid Dasti, a senior police officer in Karachi. He said police lobbed tear gas canisters and dispersed the mob, but protesters later regrouped and set fire to a gas station.
Some rioters also fired shots, wounding two people on a nearby bridge. Police arrested four people, Dasti said.
Rioting and protests were also reported in Kandh Kot and Khairpur, two other cities in Sindh province, senior police officer Sanaullah Abbasi said, but no major injuries were reported.
Police said Haideri was killed over a personal dispute, but retaliatory violence can spring up between Sunnis and Shiites in the wake of such attacks.
Pakistan banned Sipah-e-Sahaba after the Sept. 11, 2001, attacks as part of efforts to purge the country of extremism, but the group still operates more or less openly. Al Qaeda and the Taliban are also extremist Sunni groups and share Sipah's anti-Shiite stance.
