Pakistani opposition leader Imran Khan called on his supporters to take to the streets across the country after at least three people were killed in clashes between protesters and police in the capital Islamabad overnight.
The violence erupted late on Saturday after thousands of protesters tried to march on Prime Minister Nawaz Sharif's residence, prompting police to fire tear gas to stop them.
Demonstrators demanding his resignation have camped outside government offices for more than two weeks but it was the first time violence broke out as protesters, some armed with sticks and wearing gas masks, tried to break through police lines.
The eruption of violence has unnerved many in the coup-prone country, with Mr Sharif looking increasingly cornered amid relentless calls by the opposition for him to step down.
Small skirmishes continued into today and protesters were also expected to rally in the streets of Karachi later in the day, but no major acts of violence have been reported.
Mr Khan, an outspoken cricketer-turned-politician, told his supporters he would not back down from his demand for Mr Sharif to resign and called on more protesters to join him.
"I am prepared to die here. I have learnt that government plans a major crackdown against us tonight," he said. "I am here till my last breath."
At least three people were killed and 200 wounded overnight, hospital officials said.
The violence broke out despite the army's public intervention in the conflict. How the crisis unfolds ultimately lies in the military's hands in a country ruled by generals for half of its entire history.
Highlighting the urgency of the situation, army chiefs were expected to meet later on today to discuss the crisis, prompting speculation that the army could take decisive action to end the crisis.
Mr Sharif, who swept to office in the country's first democratic transition of power last year, has firmly resisted opposition calls for him to resign while agreeing to meet their other demands such as an investigation into alleged fraud during last year's election.
Having been ousted himself in a coup in 1999 during an earlier stint in office, Mr Sharif still has a difficult relationship with the army.
Even if he survives this crisis, he will remain significantly weakened and sidelined on key issues such as foreign policy and security.
Opposition leader and cleric Tahir ul-Qadri, thousands of whose supporters have rallied alongside Imran Khan, said protests would not subside unless Mr Sharif resigned.
"State atrocities have reached their peak," he told his supporters from atop a shipping container. "Imran khan and Dr Qadri are fighting this war together."