ISLAMABAD (REUTERS, AFP) - An anti-government Pakistani cleric told his protesting supporters camped outside parliament on Wednesday not to allow anyone in or out of the assembly, which is in session with Prime Minister Nawaz Sharif in attendance.
"Don't let all those inside come out and don't let anyone go in," the cleric, Mr Tahir ul-Qadri, told his supporters outside parliament in the capital, Islamabad.
Mr Qadri and opposition politician Imran Khan are trying to force Mr Sharif to resign over allegations of election rigging and corruption. After five days of protesting in Islamabad, they led supporters past shipping container barricades to reach parliament.
Despite fears of violence - many protesters were equipped with gas masks and batons - riot police and other security forces looked on without intervening.
The standoff has added to the sense of instability in a country struggling with a homegrown Taliban insurgency, crippling power crisis and sluggish economy.
It has also raised fears that Pakistan's fragile democracy could be under threat of military intervention - the country of 180 million people has seen three coups since its creation in 1947.
Rumours have abounded that elements within the influential military have been behind Mr Khan and Mr Qadri's moves, though the cleric and the interior minister have adamantly denied this.
On Tuesday, Mr Khan had threatened to break into the PM's official residence if Mr Sharif did not resign, calling on his supporters to gather at 4:00 pm (7pm Singapore time) Wednesday.
Mr Qadri, however, distanced himself from Mr Khan's call, saying his supporters would maintain a peaceful sit-in until Mr Sharif stepped down.
Early on Wednesday, the army's chief spokesman called for dialogue.
"Situation requires patience, wisdom and sagacity from all stakeholders to resolve prevailing impasse through meaningful dialogue in larger national and public interest," General Asim Bajwa said through a recognised Twitter account.
The session of the lower house of parliament, attended by Mr Sharif, began as thousands of protesters camped outside, many having slept overnight on the roadside.
"The pressure is very strong, and god willing the army chief will tell Nawaz and his brother Shahbaz (chief minister of Punjab province) to go," said protester Basharat, a supporter of Mr Khan's Pakistan Tehreek-e-Insaf (PTI) party.
Mr Qadri repeated his demand for Mr Sharif to quit and install a "national government", and ordered his followers to stop lawmakers leaving.
"Block the gates of parliament. Nobody should be able to come out and nobody should be able to go in," Mr Qadri said.
Mr Sharif has a history of testy relations with the military - his second term as PM ended abruptly in 1999 when then-army chief Pervez Musharraf seized power in a coup.
His government is thought to have angered the military further by pursuing criminal cases against Musharraf dating back to his 1999-2008 rule, including treason charges.
Military analyst Ayesha Siddiqui warned that the situation was very precarious.
"From the military perspective, they have tried and tested Nawaz Sharif a third time and they feel disapointed. Why would they let him be?" she told AFP.
Meanwhile Pakistan's Supreme Court on Wednesday ordered Mr Khan and Mr Qadri to appear in court the following day over their protests. "We would like to give notice to all respondents for tomorrow," Chief Justice Nasir ul-Mulk said in response to a petition filed against Khan and Qadri over their protests.
The United States, Britain and the European Union have all voiced support for Pakistani democracy and urged the feuding sides to negotiate to find a way out of the impasse.
Last year's election, rated free and credible by international observers, was an important landmark for Pakistani democracy - the first time one democratically elected government had completed its term and handed over power to another.
Mr Sharif's Pakistan Muslim League-N (PML-N) party has accused Mr Khan and Mr Qadri of trying to derail democracy.