Muslim leaders gathered for a rare summit in Islamabad as militant attacks killed 36 people across the country on one of the deadliest days of violence in months.
The string of attacks on Shiite Muslims and Pakistani security forces underscored the immense security challenge in a country where Taliban and Al Qaeda-linked extremists bitterly oppose the US-allied government.
Twenty-three people were killed and 62 wounded overnight Wednesday in Rawalpindi, the twin city of Islamabad, where Iranian President Mahmoud Ahmadinejad and Turkish Prime Minister Recep Tayyip Erdogan are chief among the summit guests.
Police said a suicide bomber struck a procession of Shiite Muslims who were commemorating the holy month of Muharram, which is frequently targeted by sectarian extremists in Pakistan.
Police used lamps and torches to work through the night, and confirmed the final death toll after daybreak with eight children among the wounded.
It was the deadliest bombing in Pakistan since 29 people were killed in the northwestern district of Khyber on June 16 and the worst attack on Shiites since February 17, when a suicide bomber killed 31 in northwestern Kurram.
The Pakistani Taliban claimed responsibility for the attack, another explosion Wednesday that killed two people in Karachi, and attacks targeting security forces in the northwest that officials said left five police dead.
Spokesman Ehsanullah Ehsan told AFP that Shiites are "defiling the Prophet." The Taliban have
been fighting an insurgency against security forces since 2007, one of the chief reasons why Pakistan so rarely hosts international events.
Human rights groups frequently criticize the government for failing to clamp down on extremist Sunni Muslim sectarian groups, such as Lashkar-e-Jhangvi, which have been accused of killing thousands of Shiites.
But Pakistan has been determined that Thursday's Developing Eight (D8) summit will present a different image of the country as it gathers together Bangladesh, Egypt, Indonesia, Iran, Nigeria, Malaysia, Turkey and Pakistan to promote trade.
The government has said it wants the summit to strengthen its international standing and help "remove misconceptions (about the country) created in a section of international media."
The capital was in lockdown to safeguard the event. Thousands of extra police and paramilitaries were deployed. Schools were closed. Thursday was declared a partial public holiday and motorcycles were banned close to government installations.
And on the outskirts of Peshawar, militants attacked a police post Thursday, killing one police official and abducting another, police said.
There was no claim of responsibility for that attack.