The mosque has been at the forefront of a vigilante campaign to enforce a form of Islamic Sharia law in Pakistan. Its students have kidnapped police officers and people they accuse of involvement in "immoral" acts such as prostitution.

Cleric captured
There were about eight explosions over a period of several minutes, according to eyewitnesses. "All people in the mosque should surrender or they will be responsible for losses," said the police warning broadcast over loudspeakers, according to witnesses quoted by Reuters news agency.

On Wednesday, hundreds of students were allowed to leave the mosque after they were screened by police. One of the mosque's senior clerics was captured by police as he tried to leave the building disguised as a woman.

Maulana Abdul Aziz was caught wearing the burqa, an all-enveloping sheet-like dress adopted by some Muslim women. A security official told the AFP news agency the cleric was noticed because his height and his large stomach set him apart from the women he was with. Pakistani President, Gen Pervez Musharraf, has long been criticised for failing to clamp down on the mosque's activities.

The latest confrontation reportedly started when security forces tried to place barriers around the mosque. On Tuesday, women students of one of two seminaries attached to the mosque protested in the street, while their male counterparts traded gunfire with security forces. At least 16 people died in the violence and scores were hurt.