Allies of the US-backed leader seized on this week's bloodshed in Karachi and a pair of assaults on two former ministers to justify a boycott of parliament, and accused the government of persecuting them.

Parties opposed to Mr Musharraf swept to power in February elections and have formed a four-party government committed to clipping Musharraf's already diminished powers.

The elections were supposed to cement Pakistan's return to democracy after eight years of military rule under Musharraf, who retired as army chief in November. But a string of violent incidents and a sharp chill in the political climate threaten more instability as the country faces the twin threats of Islamic militancy and a faltering economy.

Ten people died in Karachi on Wednesday when a brawl among groups of rival lawyers was followed by a spasm of shooting and arson, the worst political violence since the Cabinet was sworn in last week.

Six of the victims died in a burning office block.

On Thursday, opposition parties who last week helped Prime Minister Yousaf Raza Gilani secure an unprecedented unanimous vote of confidence lined up outside parliament to complain of 'political victimization.'

'We cooperated with the government with positive thinking to strengthen democratic institutions. Now you can see what they are doing with us,' opposition leader Chaudhry Pervaiz Elahi said.

He blamed the party of Mr Nawaz Sharif, the second biggest player in the coalition and a fierce critic of Musharraf.

Inside the National Assembly, Mr Gilani also adopted his strongest political rhetoric so far.

He said the government would not allow the 'sacrifices' for democracy made by his assassinated party leader Benazir Bhutto and her politician father - who was hanged in 1979 after an army coup - to be 'compromised at the behest of dictatorship, conspiracy and violence.'

He appealed to political parties and citizens to 'exercise tolerance, practice accommodation and adhere to the law. If we do not do that, we may again be subjected to the dark years of tyranny and dictatorship from which we have just started to come out.' -- AP