The chief cleric of the controversial Lal Masjid in Islamabad on Tuesday declared jihad after an exchange of fire between students and Pakistani security forces, Dawn News channel reported.
He also ordered Lal Masjid militants to launch attacks on forces.
Witnesses verified that Lal Masjid militants destroyed some posts set up by government security forces. Some government buildings were also under attack from the religious students.
At least three policemen were reported injured after Lal Masjid students exchanged fire with security forces.
Hundreds of students took to the street in protest, chanting pro-jihadi slogans. Security forces opened fire that triggered retaliations from the students.
Pakistan had on Monday deployed more forces near the mosque to tighten security around it, Dawn newspaper reported on Tuesday.
The move has brought the total number of Rangers deployed around the mosque to 1,500, with 500 police commandos in support.
The newspaper, quoting informed sources, said the authorities of the mosque have also reinforced security of its brigade, which is equipped with advanced weapons and wireless systems, and threatened to raid more massage centres in the city.