Speaking to thousands of supporters on Sunday, the former cricketer-turned-politician Imran Khan urged discontent Pakistanis to do more than participate in street protests against the government.

"There is only one way to get rid of this government, which is to launch a civil disobedience campaign from today," Khan told demonstrators in the capital city, Islamabad.

"I urge the nation not to pay taxes and utility bills from now onward," he said, adding that protesters would march on parliament in two days if Prime Minister Nawaz Sharif had not resigned.

Anti-Taliban cleric Tahir ul-Qadri, who also amassed thousands of followers in Islamabad this weekend, joined Khan's message in calling on voters to procure their freedom from the government through action.

"We don't want midterm elections ..." the cleric said. "What we want is revolution. We will not allow this system to continue any more."

An estimated 25,000 people participated in Sunday's protest, more than double Saturday's turnout.

The dual rallies, though still not reaching the 1 million target hoped for by the opposition politicians, have brought business to a standstill in downtown Islamabad since they began late last week.

Sharif won a landslide victory last year, garnering a third term as head of government. During the 1990s, he led as premier twice before going into exile as a result of the 1999 military coup. He has refused to resign, raising fears that the military will step in if both of the protest leaders and the head of government remain inflexible.

Last year's polls marked Pakistan's first successful democratic transfer of power since its statehood in 1947.

kms/mkg (AP, AFP, dpa)