Protesters led by opposition leaders Imran Khan, a hero cricket player-turned-politician, and Tahir ul-Qadri, a firebrand cleric, have been on the streets for weeks trying to bring down the government of Prime Minister Nawaz Sharif.
Protests descended into deadly chaos over the weekend, with demonstrators clashing with police in a central area near government buildings and embassies. Three people died.
Mr Sharif, who was toppled by the army in a 1999 coup but staged a comeback with a big election win in May last year, has refused to quit while protest leaders have rejected his offers of talks, creating a dangerous deadlock.
Clashes broke out early yesterday and continued sporadically throughout the day. The state PTV channel and its English-language PTV World service were taken off the air after protesters stormed its headquarters.
Protesters occupied the main control room and smashed some equipment before uniformed members of a paramilitary force and soldiers secured the building and the station came back on the air.
Army chief General Raheel Sharif met the Prime Minister yesterday but it was unclear what they discussed.
Defence Minister Khawaja Asif said the government was preparing to launch a selective crackdown against protesters and warned demonstrators against storming government buildings.