Pakistan - A teenage suicide bomber killed an anti-Taliban provincial lawmaker in northwest Pakistan on Tuesday after walking into the official's house along with guests and blowing himself up.

More than a dozen people were wounded in the attack in Swat valley, police said.

The army, battling a Taliban insurgency, launched what it said was a successful offensive in Swat in late April that cleared most of the area, but it still faces pockets of resistance.

Nuclear-armed Pakistan is under growing U.S. pressure to crack down harder on militants in border areas to help it fight the Taliban in Afghanistan, where President Barack Obama is expected to send 30,000 more troops to try to put down an insurgency.

That may be difficult because Pakistani President Asif Ali Zardari faces growing calls to relinquish many of his powers and analysts say it's up to the country's powerful military to decide whether to intensify the fight against militants.

The slain lawmaker, Shamsher Ali, was a member of the Awami National Party, part of a coalition that rules the North West Frontier Province. Police said two of his brothers were wounded in the attack, one critically.

People were coming to exchange Eid greetings with him when a man came and blew himself up, his relative Farooq Khan said, referring to the Muslim holy festival which ended on Monday.

Police said the bomber's head and parts of his body were found in the reception area of Ali's home. Militants had destroyed another one of his homes earlier this year.

Security forces have killed more than 2,000 fighters in the Swat Valley, about 120 km (80 miles) northwest of Islamabad, in the offensive, according to the army. There has been no independent verification of that casualty estimate.

Hundreds have been killed in retaliatory bombings since Pakistani forces attacked the militant stronghold of South Waziristan, part of a tribal region seen as a global militant hub, in October. Many militants were believed to have fled.

The leader of the Taliban in Swat and self-styled cleric Fazlullah telephoned the BBC last month to say he had escaped to Afghanistan and would soon launch raids against the army. The army said in July he was believed to have been wounded.

The attack that killed Ali occurred in a village that was a former headquarters of Fazlullah.

(Writing by Michael Georgy; Editing by Jeremy Laurence)