Pakistani Prime Minister Nawaz Sharif chaired a joint session of parliament on Tuesday as a deepening crisis over mass protests demanding his resignation prompted fears of an army intervention.

Sharif had called the session and he had been expected to address it on Tuesday but as members of parliament streamed into the assembly, his office clarified that the proceedings would last all week.

"Everyone will be given a chance to speak and after that he may address the parliament," a Sharif spokesman said.

Pakistan has been in turmoil since mid-August when tens of thousands of protesters led by Imran Khan, a former hero cricket player, and outspoken cleric Tahir ul-Qadri gathered in the capital Islamabad refusing to leave unless Sharif resigns.

Demonstrations turned violent and chaotic over the weekend as protesters armed by clubs and wearing gas masks against teargas tried to storm Sharif's residence. Three people were killed and hundreds wounded.

The chaotic scenes in the usually orderly Pakistani capital have unnerved a nation where power has often changed hands through military coups rather than elections, prompting speculation that the military was prepared to intervene again.

Few expect the army to actually seize power this time but many believe it is using the protracted crisis to weaken Sharif and take control over key security and foreign policy issues such as relations with India and Afghanistan.

By convening a joint session of parliament, where Sharif has a solid majority, the prime minister seeks to reaffirm that he is fully in control of the situation. He and his aides have repeatedly said he would not quit.

Clashes continued into Monday, with hundreds of people storming and ransacking the state television headquarters in central Islamabad, prompting the army to step in to clear and secure the building.

But the capital was quiet on Tuesday, with no reports of violence and a crowd of a few thousand protesters massing peacefully in the so-called Red zone - a central area where Sharif's office, parliament and many embassies are located. - Reuters