Police in Pakistan say they arrested about 150 opposition activists on August 19 as mass demonstrations in Islamabad against Prime Minister Nawaz Sharif entered a fifth day.
Opposition leader Imran Khan and conservative Islamist cleric Tahir ul-Qadri have led tens of thousands of their supporters from across the country into Islamabad.
Their twin protests are separate but are both aimed at bringing down the government of Sharif, whom they accuse of corruption and rigging elections.
Khan has threatened to lead protesters on August 19 into Islamabad’s high-security "red zone" as his 48-hour deadline for the government to step down ends.
Interior Minister Chaudhry Nisar Ali Khan has said demonstrators would not be allowed to enter Islamabad's red zone -- which is the location of the parliament, government buildings, and Western embassies as well as the presidential and prime minister's offices.
The area has been cordoned off with container cars and barbed wire and is packed with riot police and paramilitary forces.
Qadri and Khan say hundreds of their supporters have been arrested during the past week.
Meanwhile, Khan's Pakistan Tehrik-e Insaaf (PTI) party has announced that its lawmakers have all decided to resign from the 34 seats they control in the country's National Assembly.
The party, which is the third largest in the country, also said its lawmakers would resign from all provincial parliaments with the exception of the legislature in Khyber Pakhtunkhwa Province, which the party controls.
That announcement means Pakistan will have to organize a raft of fresh elections.
Khan has rallied tens of thousands of supporters in Islamabad in recent days, but his protest has failed to attract the hundreds of thousands of demonstrators that he had promised to mobilize.
On August 18, other opposition parties distanced themselves from Khan's appeal for civil disobedience, which included a call for citizens to refuse to pay their utility bills or taxes as long as Sharif remains in power.
With reporting by Reuters, AP, AFP, and "Dawn"