A bomb killed a Pakistani provincial minister and at least 16 other people on Sunday at the minister's home in the political heartland of Prime Minister Nawaz Sharif, Punjab province officials said.

Police said the blast caused the roof to cave in as Punjab Home Minister Shuja Khanzada held meetings with around 20 people in his hometown of Attock in northern Pakistan.

Two suicide bombers also died in the attack and several people were still missing and presumed to be under the rubble, Punjab Law Minister Rana Sanaullah said.

Salman Rafiq, provincial health adviser for Punjab, said Khanzada had died. Punjab is Pakistan's biggest and wealthiest province and Attock is located at its northern tip, on the road between Islamabad and Peshawar.

"There were between 20 and 30 people present when the blast took place," district information officer Shahzad Niaz told Reuters. "The roof collapsed."

Rescue workers at the scene said nine bodies had been recovered so far.

A Taliban-affiliated militant group, Lashkar-e-Islam, claimed responsibility for the attack and said it was retaliation for military operations against them.

"Such types of attacks will continue in the future," group member Saluddin Ayubi told Reuters.

It was unclear if Lashkar-e-Islam, based mainly in the tribal areas along the Afghan border, had actually carried out the attack or was just taking credit for it.

If the claim was true, the bombing would represent a significant development in the group's ability to strike at high level targets. Such large attacks are more usually the hallmark of the Taliban or banned sectarian group Lashkar-e-Jhangvi.

Pakistan, a nuclear-armed nation of 190 million people, is plagued by a Taliban insurgency, criminal gangs and sectarian violence.

Punjab has traditionally been more peaceful than other parts of Pakistan. Sharif's opponents have accused him of tolerating militancy in return for peace in his province, a charge he hotly denies.

Two weeks ago, Punjab police killed the leader of Lashkar-e-Jhangvi, along with his two sons, deputy, and 10 other supporters.

Police described the incident as a shootout as he sought to escape from custody, but many insiders say the shooting had the hallmarks of an extrajudicial killing.