At least 23 people were killed Pakistan's commercial capital Karachi as the supporters of President Pervez Musharraf and suspended Supreme Court chief justice Iftikar M Chaudhry clashed.

Chaudhry's sacking has snowballed into the worst crisis Musharraf has seen since he captured power eight years ago.

The violence, which began on Saturday morning before Chaudhry's arrived to address a gathering of the Sindh high court bar association and a planned rally by the Muttahida Quami Movement -- a coalition partner in Musharraf's government -- escalated into gun-battles between rival groups in at least six different parts of the city.

Musharraf is also scheduled to address a rally in front of Parliament in the capital Islamabad.

Police sources, officials of the Edhi Trust, a leading welfare organisation, and eyewitnesses said the death toll had risen to 23 and it could be higher as the gun-battles were continuing unabated in areas surrounding or adjacent to Shahrah-e-Faisal road, the artery of the city and which links the airport to the city. More than 100 people were also injured in the clashes.

The Sindh home secretary, however, confirmed seven deaths and 21 injuries.

"We have seen some bodies and also wounded people on the roads, but since the firing is continuing we can't remove them," an Edhi trust official said. "We have also lost a driver, Faiz-ur-Rehman who was driving an amublance to Malir city."

Geo Television reported a blast in the congested area of Malir in which some people were injured.

Doctors in the two main government hospitals, Jinnah and Abbasi Shaheed, said they had treated over 35 people and received at least eight bodies.

They said the casualties had been reported from different parts of the city and all of them had died from gun shot wounds.

The opposition parties -- Pakistan Peoples Party, Jamaat-e-Islami, Pakistan Muslim League-Nawaz -- and the MQM blamed each other for firing on others' rallies in different parts of the city.

Chaudhry reached Karachi from Islamabad with his lawyers by noon but was waiting at the airport lounge for the government to ensure his safe passage to the Sindh high court via Shahrah-e-Faisal.

Firing was continuing in at least three main points of the Shahrah-e-Faisal, including Baloch Colony, FTC Bridge and Drigh Railway station.

"He [Chaudhry] will not leave the lounge until the authorities guarantee him a safe passage," his main counsel, Aitzaz Ahsan, said.

There had been fears of a major clash between the opposition parties, which have skillfully exploited the presidential reference against the suspended chief justice to launch a movement to oust Musharraf, and the MQM, a strong force in Karachi, for the last few days.

Chaudhry had earlier refused to listen to an advice from the interior ministry to postpone his visit to Karachi.

The MQM, which is in power in the provincial and city governments, also made it clear it would not cancel its rally which it says would be a show of strength against the forces trying to use the judiciary issue to destablise the federal government.

Sindh's Home Affairs Adviser Waseem Akhtar blamed the chief justice for the clashes in the city and said the provincial government would ask the president to file another reference against him for instigating violence.

Amjad Malik, a photographer for a local daily, who was present near the FTC bridge where fierce fighting took place between rival groups, said there were no police personnel or rangers to control the situation.

The television channels, which showed live pictures of the firing from Gurumandir, a busy commercial area of the city, Kala Board, Malir, Landhi and PIB colony also noted that the law enforcement agencies were mere spectators as the political workers had a free hand against each other.

Unidentified men in jeans and T-shirts and Shalwar Kameez were seen exchanging heavy fire behind cars.

Edhi sources said that many petrol pumps had also been set on fire in some parts of the city while over three dozen cars, wagons and motorcycles were torched and their wreckages were still burning.

Pakistan's Interior Minister Aftab Sherpao, who survived an assassination attempt by a suicide bomber in Charsadda town in North West Frontier Province few days back, said the provincial government had done everything to ensure security in the city but some people were busy trying to disrupt the peace.

"We are trying to get the situation under control. What has happened is unfortunate. We will also try to provide a safe route to the chief justice in waiting," Sherpao said.

The MQM claimed several of their rallies converging for the main rally had been fired upon.

On Friday night, two persons belonging to Pakistan Muslim League-Nawaz were killed in Malir and Shah Faisal Colony.

Later a central leader of the Sunni Tehreek religious party was also shot dead in Landhi.

Lawyers and some opposition parties had also assembled to stage a sit-in in front of the Corp Commander's office in Karachi as they said police and rangers had failed to provide the suspended chief justice and his followers protection from MQM supporters.

Airline officials said that due to the violence, international and domestic flights had been severely disrupted.

Local television channels showed footage of people from rival groups carrying machine guns and firing at each other.

One person, heavily bleeding with injuries, was seen crying for help from a bus.

Armed men beat cameramen of private TV channels and asked them not to shoot films of the firing. Geo TV said that one of its cameramen was also beaten up and his camera snatched.

Besides, some 20 vehicles -- both official and private -- were burnt in different localities.

Several petrol stations were also set afire.

A female anchor of a private TV channel said that armed men entered the office and asked the staff to stop showing the footage of firing.

Officers from the paramilitary forces took the suspended chief justice to a corner of the passenger lounge at the airport and requested him to go in a helicopter to the building of the Sindh high court, media reports said.

In Islamabad, thousands of pro-Musharraf supporters have begun arriving to attend a rally to be addressed by him.

Meanwhile, unidentified gunmen attacked the office of private Aaj TV channel in Karachi, its Director News Talat Hussain said.

Hussain, who was in the office when it was attacked, said that heavy arms were used to target the Aaj TV. However, no one was hurt as all staff members lay down during the firing which lasted for more than 15 minutes.

"It seems to be ... a deliberate firing," Hussain said, adding the windows of the office were smashed in the attack.

He said that the armed men later occupied nearby buildings of the private TV channels and took positions.

Hussain said that police and other security agencies were informed about the attack but no security was provided to them hours after the incident.

He said that 500 staff members were inside the office.