Hundreds of demonstrators hurled rocks and bottles at paramilitary troops and police outside the Supreme Court, where Chief Justice Iftikhar Mohammad Chaudhry was due to attend a hearing into misconduct charges.

Violent clashes also broke out in the eastern city of Lahore despite overnight raids by police across the country that seized lawyers, opposition party activists and Muslim hardliners.

Military ruler President Pervez Musharraf drew international condemnation when he sacked Chaudhry last week, a move that also set off days of rallies and intensified Islamist and secular opposition anger over his leadership.

The opposition says Musharraf is trying to intimidate the judiciary before they hear key issues -- including his planned re-election by parliament and his dual role as president and army chief -- later this year.

The United States, the military ruler's close ally in the "war on terror", said the judicial dispute was a "matter of deep concern" while rights groups have warned of a constitutional crisis in Pakistan.

"This is the beginning of the end of president Musharraf, his cronies and collaborators," said Khwaja Asif, a senior leader of former premier Nawaz Sharif's Pakistan Muslim League party at the protest in Islamabad.

In Islamabad police seized Qazi Hussain Ahmed, the president of Pakistan's main alliance of religious parties, the Muttahida Majlis-e-Amal (MMA) or United Action Front, when he tried to break through a cordon, AFP reporters said.

Security forces erected barbed wire and concrete barricades to seal off the Supreme Court but hundreds of people including lawyers entered the court compound as Chaudhry arrived, a reporter said.

A crowd of around 1,000 people outside the court chanted "Down with Musharraf dog", "Go Musharraf go" and "Allahu Akbar (God is Greatest)" and waved black banners.

Ahmed -- a fundamentalist and vocal opponent of Musharraf because of his failure to restore full democracy and his ties to Washington -- had earlier led a session of Friday prayers in front of parliament lodges.

Police also tear-gassed and baton-charged opposition workers who came out of a mosque near a key intersection in the eastern city of Lahore, as well as lawyers outside Lahore High Court, witnesses said.

The opposition rally in Lahore was also attended by former president Rafiq Tarar, they said. More than 50 people were arrested, witnesses said.

In the northwestern city of Peshawar around 1,000 people joined a rally attended by both Islamists and secular parties, while some 300 lawyers marched in Karachi, Pakistan's largest city, witnesses said.

Security forces earlier rounded up nearly 100 lawyers and Islamists across the country in a bid to stifle the protests.

Chaudhry has denied the charges against him and questioned the constitutionality of the judicial council, and said he was roughed-up by police after refusing an official car on the way to an earlier hearing.

Pakistani media said they were under pressure not to portray Chaudhry as a "hero". A private television channel said it had been barred from airing a popular news programme, which featured discussions of the crisis.

Information Minister Mohammad Ali Durrani earlier denied that the snowballing crisis had prompted the government to suspend the country's mobile telephone and Internet networks following reports of nationwide disruption.

In further international reaction a group of 70 British lawyers, including Prime Minister Tony Blair's wife, said reports of the "humiliating treatment of the chief justice of Pakistan" was causing "great international unease."

Musharraf spoke about the issue for the first time on Thursday, telling a public meeting that he would accept whatever decision emerges from the ongoing judicial inquiry and that he would address the nation on the outcome.