More than 1,000 people from Pakistan's Shia Muslim minority were in the Zainabya mosque at the time of the blast, police said.

"It was a suicide attack," Nisar Ahmed Saroya, district police officer for Sialkot, told Reuters. "It was a massive explosion which was heard several miles around.

"Fourteen people were killed on the spot and eleven died at hospital," Saroya said from Sialkot, some 100 miles southeast of Islamabad on the border with India and near the city of Lahore.

The explosion created a crater more than 60 cm deep, said private GEO Television channel.

Police said bodies were blown to pieces.

"The floor of the mosque is strewn with blood and human flesh," Saroya said.

Several hundred angry Shia rampaged through the town after the explosion, hampering relief operations and police who were trying to investigate the blast.

The mob set fire to a gas filling station and two police vehicles, and hurled stones at buildings in the neighborhood, police said.

No group has taken responsibility for the blast against Shia Muslims, who account for 20 percent of Pakistan's 150 million people.

However, Sunni Muslim extremists were blamed for a series of attacks on Shia mosques in the southern port city of Karachi earlier this year.

Some of these Sunni groups have forged close links with Osama bin Laden's al-Qaeda network and have been used to launch attacks against Pakistani leaders in retaliation for Islamabad's support for the US-led war on terror since the Sept. 11, 2001 attacks.