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ISLAMABAD - Pakistani authorities imposed a curfew around a mosque on Wednesday where 11 people were killed in clashes between religious students and security forces and ordered students in the mosque to lay down their weapons.

Violence erupted on Tuesday outside the mosque in the capital, Islamabad, which has become the headquarters for hardline religious students, campaigning for observance of strict Islamic law, who have been confronting authorities for months.

Liberal politicians have been pressing President Pervez Musharraf to crack down on the Taleban-supporting students and their clerics, who have threatened suicide attacks if action was taken against them.

The government had refrained from using force for fear it could provoke suicide attacks, or lead to casualties among female students at a religious school, or madrasa, in the mosque compound.

Sporadic firing between paramilitary forces and the student militants inside the Lal Masjid, or Red Mosque, rang out all Tuesday afternoon and through the night in the heart of the leafy capital.

The Interior Ministry said nine people were killed but hospital officials later said the toll had risen to 11.

Deputy Interior Minister Zafar Warraich told an early Wednesday news conference broadcast live on television a curfew had been imposed in the neighbourhood around the mosque.

Speaking after Musharraf held a meeting with top security officials, Warraich said warnings would be broadcast over loudspeakers immediately for the students holed up inside the mosque to lay down their weapons and surrender.

No action would be taken against those who did but anyone who tried to fight would be shot, he said.

"A bullet will be responded with by a bullet," he said.

Asked if security forces would launch an assault on the fortified mosque compound, he said: "We are not going to go inside and attack. We want them to come out and surrender."

The violence comes at a bad time for Musharraf who has been facing a campaign against him by lawyers and the opposition since he suspended the country's top judge in March. He is also preparing for a presidential and general elections.

The clashes erupted on Tuesday when about 150 students attacked a security post at a government office near the mosque, snatched weapons and took four officials hostage, police said.

Paramilitary forces fired teargas to disperse hundreds of students outside the mosque, and then came under fire.

Someone in the mosque later used a loudspeaker to call for suicide attacks, though a cleric there denied to Reuters that any such order had been given.

About 150 people were taken to hospital on Tuesday, 30 with bullet wounds, others suffering from teargas.

The 5000 or so students affiliated with the mosque range in age from teenagers to people in their 30s, many from conservative areas near the Afghan border. They study under firebrand clerics and have been campaigning against vice and for Islamic law.

It was not known how many students were inside the mosque compound on Tuesday night but there were believed to be at least several hundred there. Earlier, many women students were seen leaving the mosque and anxious parents turned up outside to take their children home.

Soon after dark, power was cut to the whole neighbourhood around the mosque and soldiers joined paramilitary troops sealing off streets.

Authorities said journalists should also leave the area around the mosque.

Trouble began at the mosque in January when students occupied a library next to their madrasa to protest against the destruction of mosques built illegally on state land.

They later kidnapped women, some from China, at two places they said were brothels. They also abducted police.

- REUTERS