A suicide attack outside an Islamabad hotel claimed the lives of 13 people and wounded 71 near a hotel as authorities reclosed the controversial Red Mosque.

Authorities ordered the mosque, a hotbed of Islamist radicalism, closed indefinitely after radical students temporarily took over the disputed complex when it reopened Friday.

Angry over the assignment of a cleric from another mosque, the students daubed red paint on the walls (it had been repainted yellow after deadly clashes there two weeks ago) and put up a black flag with two crossed swords -- a symbol of jihad.

The students then battled with police. The students threw stones and the police responded with tear gas. While that was going on, a thunderous blast erupted about 400 metres from the mosque.

The deadly blast was set off  in the open-air restaurant of the Muzaffar Hotel, located in a market district. Javed Iqbal Cheema, a senior Interior Ministry official, said seven police officers died in the blast. He said it was a "pre-planned bombing" designed to target police officers.

"If these people had not created such a situation, it would not have happened," he said of the protesters, adding the mosque was now closed again.

Television footage showing widespread carnage from the attack, with many of the victims bleeding or badly burned, and being carried from the wreckage and piled into ambulances.

There has been no claim of responsibility yet.

Islamabad has been attempting to return to normal after a siege at the mosque that ended just over two weeks ago left more than 100 dead.

The government partially repaired the damage caused by the conflict and hoped the mosque's reopening would calm things further.

Cleric's return demanded

During the Friday confrontation at the mosque, the students demanded the return of pro-Taliban cleric Abdul Aziz -- who is being detained by the government. His brother, Abdul Rashid Ghazi, died in the siege.

The students forced a government-appointed cleric, intended to lead prayers, to retreat. The prayers were eventually led by another cleric associated with the mosque and the government-appointed cleric was escorted from the compound.

The angry crowds also shouted insults against President Pervez Musharraf.

At the mosque's main entrance, Liaqat Baloch, deputy leader of a coalition of hardline religious parties, the Mutahida Majlis-e-Amal, condemned Musharraf as a "killer" and called for an Islamic revolution in Pakistan.

Meanwhile, television footage from inside the mosque showed scenes of pandemonium, with crowds of men in traditional Islamic clothing shouting angrily and throwing fists in the air.

While Friday's demonstrations were happening, police stood on the street outside but did not enter the compound.

Islamabad commissioner Khalid Pervez said the situation was under control and police were simply trying to minimize tension.

Security had been tightened in the capital ahead of the mosque's reopening. Extra police took up posts around the city and airport-style metal detectors were put in place at the mosque entrance, used to screen worshippers for weapons.

The Red Mosque siege has triggered unrest, primarily in the Taliban-dominated tribal areas of northwest Pakistan. More than 300 people, mainly police and soldiers, have died in bombings since the siege ended July 10.

A July 17 suicide attack in Islamabad killed 16 at a rally in support of the country's top judge.

In the period leading up to the siege, which ended with the storming of the mosque, clerics had enlisted thousands of its students in a campaign to impose Taliban-style Islamic rule in Islamabad. The group kidnapped alleged Chinese prostitutes and threatened to use suicide attacks to defend the compound.

Militants holed up in the compound for a week before the army attacked.

The government claims that the majority of those killed in the siege were militants, but many Pakistanis have expressed doubts about the government's casualty figures, claiming many were actually women and children.

With files from The Associated Press