The suicide attack happened at a hospital in the troubled town of Dera Ismail Khan on Tuesday as Shiite Muslims gathered to protest over the death of a man in a suspected sectarian attack.

“The death toll has risen to 30 after seven more blast victims died in hospitals,” local police official Malik Mushtaq told AFP by telephone.

The dead included three policemen, he said, adding that 39 people were wounded in the blast.

Police said they had found the legs of the bomber at the blast site. They suspect the bomber could be a militant from the tribal area near the Afghan border.

“Our initial clues reveal that he (the bomber) was from South Waziristan tribal region,” a senior security official told AFP on condition of anonymity.

South Waziristan is viewed by Washington as a haven for Al-Qaeda and Taliban extremists.

The suicide attack was the first since US-backed president Pervez Musharraf resigned on Monday.

Islamabad has been under intense pressure from the United States to clamp down on militants based near the border.