Pakistani cricketer-turned-opposition leader Imran Khan staged a major rally in Islamabad on Sunday, threatening to shut down the whole country with protests as he bids to topple the government.
Khan, who alleges massive rigging in the 2013 election that swept Prime Minister Nawaz Sharif to power for the third time, has been holding demonstrations around the country since mid-August.
But his campaign has lost momentum after so far failing in its aims.
"We will close the whole of Pakistan on Dec 16," he told tens of thousands of supporters near parliament on Sunday evening, adding that his party workers would paralyse major cities starting with Lahore, Sharif's seat of power.
Khan also called for a speedy judicial probe into allegations of systemic ballot-stuffing in the 2013 poll, which saw Pakistan's first democratic handover of power and was rated by local and foreign observers as "credible".
"The ball is in your court, Nawaz Sharif -- do your talks, do your investigations and solve the issue," said the former cricket star.
Followers of Khan and firebrand cleric Tahir-ul-Qadri clashed with police in late August after they tried to storm the prime minister's residence, leaving three demonstrators dead and hundreds injured on both sides.
On September 1, the opposition groups briefly occupied the state broadcaster, raising fears the military could intervene to end the crisis as it has done in the past.
Analysts believe the protests were coordinated by the powerful army as a means of re-asserting its dominance over civilian authorities.
The protests destabilised Sharif's government and dented foreign investors' confidence, but have so far failed in their stated aim of bringing down his administration.
Qadri's followers abandoned their sit-in outside parliament last month, but the opposition movement remains a thorn in the government's side.
The administration has responded by briefly suspending pro-opposition TV channels and buying attack adverts against Khan.