Pakistan deployed paramilitary troops and police in Karachi on Thursday, a day after clashes between supporters and opponents of President Pervez Musharraf left seven people dead.
Authorities warned of "extreme action" to prevent further bloodshed in the wake of the worst violence to hit the country since a new government hostile to key US ally Musharraf won elections in February.
Angry lawyers vowed to boycott courts after it emerged that the victims of Wednesday's clashes included five attorneys, one of them female, who were burned to death inside their office.
"Police and Rangers (paramilitary troops) have been deployed in sensitive areas with strict orders to take extreme action against anyone who damages public property," Sindh province home secretary Arif Ahmad Khan told AFP.
He did not specify what form such action would take.
"The police will be responsible for security of the high court, district courts, colony of judges and offices of lawyers," he said. "We will not tolerate any laxity by police."
An inquiry had been ordered into the clashes, he added.
The violence erupted when lawyers allied to a pro-Musharraf party, the Muttahida Qaumi Movement, said they came under attack from attorneys opposed to the president while protesting against the beating of a former minister this week.
But it was unclear who was responsible for the spread of the unrest across the city.
The President of the Sindh High Court Bar Association, Rasheed Razvi, said lawyers would boycott all courts in Karachi on Thursday and accused pro-Musharraf "elements" of being behind the violence.
"This was not a clash between any groups of lawyers but a naked assault on them by goons," Razvi told AFP.
"These elements gave a message to the lawyers' community that they should give up their struggle for independence of the judiciary. But they should know that no power on earth can force us to abandon our struggle," he added.
Most of Pakistan's lawyers have strongly opposed Musharraf since he sacked the country's chief justice, the outspoken Iftikhar Muhammad Chaudhry, and dozens of other judges under a state of emergency in November.
The new government has pledged to restore Chaudhry and the rest of the judiciary, a move which would place them on a collision course with Musharraf as the judges could overturn his re-election as president last year.
But the looming showdown between Musharraf and the government has heightened tensions across the country.
Dozens of lawyers beat up former parliamentary affairs minister and key Musharraf ally Sher Afgan Niazi on Tuesday in the eastern city of Lahore, prompting a furious reaction from the president and his supporters.
Parliament is due to convene later on Thursday for a session in which the government may set out its policy on the sacked judges. (AFP)
Pakistan deploys security forces after Karachi violence