Pakistan's National Assembly has met for the first time following days of protests over the banning of Nawaz Sharif, a former prime minister, and his brother from contesting elections.
Scuffles broke out between rival MPs on Saturday showing the widening rift between the ruling Pakistan Peoples Party (PPP) and Sharif's Pakistan Muslim League-N (PML-N).
Yousuf Raza Gilani, Pakistan's prime minister, earlier appealed for calm, after violent protests erupted across major cities over rulings by the country's supreme court that went against the Sharif brothers.
Al Jazeera's Imran Khan from Islamabad said: "It was always going to be a bad- tempered affair .. but this was unprecedented.
"The PML-N spokesman and leader of the opposition said that [the] judiciary was a weapon of the government - that drew jeers from government MPs who got more bad tempered.
"It [the assembly] was called by the government because they wanted to take the sails out of the protests that were happening around Pakistan’s Punjab province ... to bring it back within the fold of parliament.
"They [the government] accuse Nawaz Sharif of agitating, of using violent protests, a charge he denies ... Both Nawaz Sharif and Shahbaz Sharif spoke to the media saying 'our supporters need not take part in violent protest'.
"The acting US ambassador for Pakistan has been inside parliament. The Americans here are very worried that any political crisis will take Pakistan's eye away from the real issue - what they say is the so-called war on terror."
Pakistani paramilitary troops were sent to Punjab on Friday after the protests erupted over the imposition of direct federal rule in the province.
Pakistan's supreme court on Wednesday barred Sharif's brother Shahbaz from elected office, effectively unseating him as chief minister of Punjab, the country's largest and most powerful province.
The court also refused to rule on an existing ban that barred Nazaz Sharif from holding elected office. The court's refusal effectively bars the former prime minister from running for office in general elections set to take place in 2013.
The development is a sign of deepening turmoil in Pakistan at a time when Asif Ali Zardari, Pakistan's president, is struggling to stave off political instability.
Sharif's government was removed in a military coup in 1999 and he was sentenced to life imprisonment for ordering the hijacking of a passenger aircraft carrying Pervez Musharraf, who then served as Pakistan's chief of army staff.
Sharif was later exiled to Saudi Arabia but returned to Pakistan in 2007 and led the PML-N to election victory in Punjab, his home province.
The party emerged as the second-largest party in the national assembly and briefly joined a coalition government led by Zardari, but then went into opposition.