Paramilitary troops have been called out in Pakistan's Punjab province to maintain order after street protests by supporters of former PM Nawaz Sharif.
Thousands of supporters of Pakistan's ex-Prime Minister Nawaz Sharif have protested at a court ban on him and his brother holding elected office.
Demonstrators are blocking roads by making bonfires in many places and raising slogans against the government.
Streets were blocked off in main cities and businesses and vehicles set alight.
Legislators of Mr Sharif's PML-N party are sitting on the stairs of the Punjab assembly after their entry was blocked.
Sharif supporters and police clashed near Rawalpindi, with unconfirmed reports of injuries.
The protests are against Wednesday's court order banning Mr Sharif and his brother, Shahbaz, from elected office.
Mr Sharif accuses President Zardari of influencing the court decision in order to remove him from politics, raising fears of renewed political turmoil.
The protests are against Wednesday's Supreme Court order banning Mr Sharif, and his brother Shahbaz, from elected office.
Mr Sharif's PML-N holds power in Punjab province where his brother was chief minister but has now been forced to step down.
Mr Sharif's PML-N holds power in Punjab province where his brother was chief minister but has now been forced to step down.
Nawaz Sharif has accused President Asif Ali Zardari of being behind the ban.
Correspondents say the court order is expected to deepen the rift between the Sharifs and the federal government and increase the chances of political instability in the country.
Correspondents say the court order is expected to deepen the rift between the Sharifs and the federal government and increase the chances of political instability in the country.
Sitting on stairs
Police on Thursday morning sealed off the Punjab assembly in the provincial capital, Lahore.
Security officials locked the gates of the assembly, laid coils of barbed wire to prevent entry and barricaded roads as hundreds of protesters shouted slogans against President Zardari, news agency AFP quoted witnesses as saying.
The decision may deepen Nawaz Sharif's rift with the ruling PPP
Reports say some legislators of the PML-N party have gathered in front of the assembly and they are holding a session on the stairs outside.
The leaders of PML-N are holding consultations at the Lahore residence of Sharif brothers to decide on a course of action against the government.
The PML-N has called on the Punjab administration officials not to carry out "illegal and unconstitutional" orders of the government.
Punjab Governor Salman Taseer held a meeting of top police and administration officials on Thursday morning to discuss the situation in the region and to devise a strategy to deal with it.
Hours after the court verdict on Wednesday night, PML-N legislators forced their way into the Punjab assembly to hold a special session.
About 120 legislators from Mr Sharif's party participated.
They passed a resolution condemning the higher judiciary and President Asif Zardari who they believe influenced the court decision.
The government said the session was illegal as federal rule had been extended to the province for two months during which the parliament would remain inoperative.
President Zardari had a late night meeting on Wednesday with Prime Minister Yousuf Raza Gillani soon after arriving in Islamabad from a four-day visit to China.
Officials say the two discussed the situation emerging from Wednesday's court decision.
Both leaders are due to attend a meeting of the top leadership of Pakistan Peoples Party in Islamabad later on Thursday to chalk out a counter strategy to PML-N's agitation.
On Wednesday, Pakistan's Supreme Court upheld bans on Mr Sharif and his brother, Shahbaz, from elected office.
Mr Sharif said it was because he would not back down in his campaign to have judges sacked by ex-president Pervez Musharraf reinstated.
The BBC's Barbara Plett in Islamabad says that the court order will deepen the rift between the Sharifs and the federal government and increase the chances of political instability in the country.
Falling out
Last June, the high court in the city of Lahore upheld an earlier ruling that barred Nawaz Sharif from running in a parliamentary by-election. The court said he was ineligible to stand because of a 1999 conviction.
Nawaz Sharif had been convicted in connection with the 1999 hijacking of a plane carrying then army chief Gen Pervez Musharraf.
The event led to Gen Musharraf ousting Mr Sharif in a coup and going on to become president.
Nawaz Sharif had returned from exile, hoping his ban from office would be lifted by a democratically elected government.
The PML-N and Pakistan's ruling party PPP then emerged as the two biggest parties after last year's elections, trouncing allies of Pervez Musharraf.
They formed a fragile coalition and managed to force Mr Musharraf out of office.
But soon after, Mr Sharif fell out with the PPP leader, Mr Zardari, and they split over the issue of the reinstatement of the judges.
