Neighbourhoods in Pakistan's largest city turned into battle zones Saturday amid widespread political violence that left 27 dead.

Government supporters and opponents traded fire in Karachi in the worst flurry of fighting since President Gen. Pervez Musharraf suspended chief justice Iftikhar Mohammed Chaudhry -- the move that triggered the unrest.

Critics have accuses Musharraf of trying to sideline Chaudhry to avoid legal challenges to his plan to seek a new five-year term later this year.

However, the government maintains Chaudhry was dismissed on March 9 because he had abused his office.

So far, Musharraf has refused to declare a state of emergency in the city of 15 million with a history of political violence.

Chaudhry was in Karachi Saturday for a rally organized by his supporters, but was unable to leave the airport and had to cancel plans and return to the capital due to the violent pitched street battles across the city.

Just one kilometre from the international airport, gunmen with assault rifles engaged in gun fights in residential neighbourhoods. Streets were blocked by shipping containers and vehicles, and several activists could be seen lying in their own blood, The Associated Press reports.

It was unclear whether the pro-Chaudhry rally would go ahead amid the violence.

Organizers had hoped the event would be the largest yet in two months of rallies in support of the ousted justice. His supporters have called for his reinstatement and for Musharraf to step down.

However, pro-government supporters have made their own show of force and had a rally scheduled in Islamabad for later Saturday that was expected to attract more than 300,000 supporters.

Musharraf urged the nation to stand united and peaceful.

Meanwhile, in Karachi, opposition supporters accused government supporters of attacking them with batons and gunfire as they tried to greet the justice on his arrival at the airport.

The claims were backed up by an AP reporter who witnessed the government supporters firing at the pro-justice activists, who fired back.

An AP tally of the city's four main hospitals found that 27 people were dead and more than 100 were injured, many with gunshot wounds.

With files from The Associated Press