Tahir-ul-Qadri, a Canadian-Pakistani Muslim leader who led a two-day protest march into the Pakistani capital, has called for a "revolution" in Pakistan, after the government ignored a deadline he set for it to resign.
Qadri addressed a crowd of tens of thousands of people gathered outside the parliament in Islamabad on Tuesday.
"We are here in front of the parliament house just to save our country from collapse and from complete ruin," he said in a his address, in which he urged supporters to continue their sit-in until Wednesday.
"We need substantial changes and reforms in our democratic political electoral system. We want to put democracy in its letter and spirit in place."
He welcomed the order issued by the country's supreme court on Tuesday to order the arrest of Pakistani Prime Minister Raja Pervez Ashraf, in connection with a corruption case.
Ashraf was declared to have "violated the principle of transparency", and the country's anti-corruption watchdog was directed to arrest him and produce him before the court by Thursday, officials said.
Abbas Nasir, former editor of the English-language daily Dawn, cited the warrant for Ashraf's arrest issued by the high court as "a noose being tightened very slowly around the government's neck".
Al Jazeera's Osama bin Javaid, reporting from the demonstration in Islamabad, said Qadri's "demands for a caretaker government to be established and the assemblies be dissolved have not been heard".
Calls for resignation
Imran Khan, the leader of the opposition Pakistan Tehreek-e-Insaf party, also announced that his party would call for nationwide protests if a caretaker government was not announced within eight days.
He demanded that President Asif Ali Zardari "resign immediately".
"The government should immediately announce new elections and should also announce a date for it," Khan told the news conference in Lahore. "Change is not possible without holding of free and fair elections," he added.
Earlier on Tuesday, scuffles occurred between police and protesters who converged on the parliament as part of the "long march" overnight, supporting Qadri in his demand of a peaceful "revolution" and the dissolution of parliament.
Qadri had given the elected government, whose five-year mandate ends in March, until 11am local time on Tuesday (06:00 GMT) to dissolve parliament.
Nasir, speaking to Al Jazeera from London, said Qadri's demands fall "well outside of the constitution and legal framework" and that the "maverick" religious leader must realise that 35 million of the nation's 91 million registered voters cast ballots in favour of the current government.
By contrast, Nasir said, Qadri has 20,000 people "out on the street" demanding change.
The supreme court, in an apparent response, issued a statement on Tuesday morning declaring that the country's elections would be held on time.
"The Pakistani capital, with a population of over a million, is at a standstill. Everything is paralysed. Schools are closed, people are in their homes," Al Jazeera's Kamal Hyder reported from Islamabad.
It was not clear who fired the shots on Tuesday morning. An AFP reporter saw police fire tear gas shells at the crowd. Protesters were brandishing sticks and had thrown stones at police around 500 metres from parliament.
The AFP reporter said protesters smashed vehicle windows.
Television footage showed police shooting into the air to push back protesters and a man on the ground being beaten by what appeared to be protesters.
Organisers of the march accused the authorities of trying to provoke them into violence.
Qadri's demand for the military to have a say in a caretaker administration and for reforms has been seen by critics as a ploy by elements of the establishment, particularly the military, to delay elections and sow political chaos.
His supporters say Qadri has given a voice to masses ruled by a feudal and industrial elite incapable of redressing a weak economy, a crippling energy crisis, armed campaigns and sectarian violence.
If held on schedule, the election will mark the first democratic transition of power between two civilian governments in Pakistan's 65-year history, which has been marked by bloodless coups and extensive periods of military rule.