"We have taken heightened security measures to prevent incidents," Khalid Pervez, the administration's official spokesman, said. "Everyone entering is being searched with metal detectors."
Trucks with antiterrorism squad commandos are stationed in nearby streets, and police are surrounding the mosque.
On July 3 hundreds of Taliban-inspired students entrenched themselves in Lal Masjid, or Red Mosque, a hotbed of Islamic radicalism in Islamabad, after clashes with government troops, and held the mosque and surrounding buildings for about a week until the July 10 army intervention.
Opposition-controlled media puts the death toll at 500, which they said included women and children.
The fundamentalist students raised a black flag over the mosque and demanded the return of a pro-Taliban cleric, Abdul Aziz, Friday who was captured while trying to flee the mosque, the Associated Press reported.
The AP said protesters clambered onto the mosque roof and daubed red paint on the walls after forcing out a cleric who had been assigned by the government to lead Friday prayers.
The mosque has been repainted beige, and the red brick walls around the building have been demolished and replaced by a chain-link fence. The nearby women's seminary, the site of the worst fighting, has been completely demolished.
Authorities have promised to rebuild the world's largest madrasa, or religious school for girls at a different site.
