Twelve people, including four policemen, were killed in a blast near the Lal Masjid in Pakistan's capital Islamabad on Friday.

While eyewitnesses said that a suicide bomber blew himself up, state-run PTV reported that a car bomb exploded killing and injuring many people.

The blast took place as police and militant students of Lal Masjid fought pitched battles after the mosque was reopened for Friday prayers nearly two weeks after security forces stormed the complex.

Hundreds of students took control of the Lal Masjid and drove out the government-appointed cleric from the mosque.

A large number of followers of Lal Masjid's sacked cleric Maulana Abdul Aziz, whose younger brother Abdul Rashid Ghazi was killed along with several militants in the military crackdown, virtually invaded the newly renovated mosque and prevented the Maulana Muhammad Ashfaq Madni from offering the Friday prayers.

Chanting pro-Jihad slogans and hailing Gazhi and others as martyrs, the crowd mostly comprised of bearded youth believed to be released students of the boys madrasa attached to the Lal Masjid demanded the police to bring Aziz, who is currently held in judicial custody, to led prayers.

Virtually shown live on the local TV channels, the violent crowd drove out Maulana Madni from the mosque. Madni was later taken to safe place by his followers.

The crowd also prevented the Jamat-e-Islami leader Liaqat Baloch from offering prayers. Baloch, whose party chief Qazi Hussain Ahmed threatened to force his way into the mosque if it was not opened for prayers today was escorted out.

Hussain, also the President of the Islamist alliance Mutahhida Majlis Amal, was no where to be seen.

Several students were seen painting the mosque, which was painted in apple green on the instruction of government, in red colour. Some students were seen flying flags of Lal Masjid on the terrace.