Hundreds of Islamists on Monday continued the siege of the heart of the Pakistani capital to denounce the hanging of the commando who assassinated the Punjab governor for alleged blasphemy.
Amid clashes with security forces, the estimated 2,000-strong gathering refused to disperse till the government meets their demands, including the implementation of Sharia, media reports said.
The army has been deployed in Islamabad's Red Zone to prevent the situation from getting out of hand.
The demonstrators were protesting against the execution of Mumtaz Qadri, who shot dead the governor of Punjab, Salman Taseer. They want Qadri should be declared a martyr.
The Sunni Tehreek and other religious outfits involved in the demonstration that began on Sunday evening want the Sharia implemented in Pakistan.
On Sunday, the government called in the army to secure the Red Zone after the Islamists, then numbering some 10,000, clashed with police and Pakistan Rangers and set fire to containers and barricades.
Police fired tear gas as the crowds gathered about 700 metres from the parliament building, The News International reported.
On Sunday, some of them beat up journalists and attacked the Karachi Press Club, accusing the media of not giving their protests adequate coverage.
The Anjuman Talba-e-Islam (ATI), student wing of Jamiat Ulema-e-Pakistan-Noorani, on Sunday staged a demonstration on the eve of 'Chehlum' for Qadri.
Witnesses and police said dozens of charged ATI workers reached the press club wearing helmets to conceal their identities.
After a heated argument with cameramen, they started smashing the windowpanes of a parked vehicle of a private news channel and then set it on fire.