Rival Pakistani political groups have exchanged gunfire in the streets of Karachi, leaving at least 15 dead and more than 50 injured.

Chief Justice Iftikhar Muhammad Chaudhry, suspended from his job by President Pervez Musharraf, had flown in to address a rally.

But the violence meant he was unable to leave the airport.

Opposition groups blamed the MQM party, which runs Karachi, of organizing the unrest, but it denies this.

In the worst violence, supporters of the pro-Musharraf Muttahida Qaumi Movement (MQM) and activists from the Pakistan People's Party (PPP) of former Prime Minister Benazir Bhutto fought gun battles for an hour.

The private Aaj TV channel showed pictures of its office under fire.

"We are under attack," said journalist Talat Hussain on air, sheltering behind a wall.

"We have seen no security force. No one has come to help us."

"It is state-sponsored terrorism. The Sindh government is responsible but we are not going to back off," said Sherry Rehman of the PPP.

An MQM spokesman denied his party was involved in the violence at the TV station.

A public holiday had been declared in the city and the streets were largely deserted.

Trapped at airport

Since his suspension on charges of "misuse of authority", Mr Chaudhry has become the focus of widespread opposition to the government of President Musharraf, who took power in a coup in 1999.

Mr Chaudhry's supporters say that President Musharraf wants the judiciary headed by a lawyer whom he can more easily manipulate.

He flew from Islamabad to Karachi on Saturday morning, planning to address a rally in the city.

But after landing, he was unable to leave the airport, because roads into the city were blocked.

One plan was for him to travel to the city centre by helicopter, but Mr Chaudhry insisted that he should be able to travel by road.

President Musharraf has ruled out a state of emergency, and appealed to the country to stand united and peaceful.

Mr Musharraf himself is due to address a rally in Islamabad later in the day.

A lawyers' spokesman told the BBC that bar association members in Karachi had been attacked by MQM activists in various parts of the city.

"Our colleagues have been brutally attacked while the government has given the MQM a free hand," he said.

"This is the end of rule of law in the country."

The Sindh High Court was surrounded by hundreds of MQM political activists.

The lawyers say that activists attacked them and prevented them from entering the high court premises where Mr. Chaudhry had been due to speak.

Photo caption

An injured man in Karachi