KARACHI - AT LEAST 39 people were killed and 25 injured when a fire ripped through dozens of homes in a shanty town in Pakistan's largest city Karachi, government and hospital officials said early on Friday.

Initial reports indicated the blaze in the teeming southern port city was sparked by a downed power wire that fell onto the roofs of the huts, said the health minister of Sindh province, Saghir Ahmed.

Fifteen children and 12 women were among those killed in the fire, which broke out just before midnight (2am Singapore time) when most residents were asleep, according to Ahmed and hospital officials.

An AFP photographer at the scene said more than 30 huts had been gutted in the massive blaze. Ahmed said the huts destroyed had been home to about 200 people.

'This is just a catastrophe. I have lost everything. My life is destroyed,' said weeping survivor Mohammed Khan, whose wife and two children were killed in the fire.

Mr Mashhood Zafar, an official at the Abbasi Shaheed Hospital in Karachi, said about half of the 25 wounded were in serious condition with severe burns.

Thick black smoke could be seen rising from the scene of the disaster in Karachi, Pakistan's commercial capital which is home to more than 12 million people.

Some residents wept as others desperately combed through the ruins looking for survivors.

Mr Mohammed Asghar was inconsolable - he lost his sister, brother-in-law and their seven children aged one to 12 in the blaze.

'My brother-in-law was a street vendor and we had planned to go to our home village in a few days,' Mr Asghar said.

'My eldest nephew has asked for a new toy car which I could not afford to buy for him. I'll regret that forever.'

The shanty town was surrounded on three sides by larger buildings, and the only escape route appeared to have been quickly blocked by the flames, firefighters said.

'Most of the casualties seem to have been caused by the lack of exit route,' said fire brigade official Ehtesham Salaam.

It took firefighters several hours to bring the blaze under control. Police have launched an investigation to determine the exact cause of the fire.

Once known for its suburban green spaces and tree-lined streets, Karachi is now a concrete jungle of haphazard settlements. More than half of the population live in slums.

The blaze appeared to be one of the biggest in recent years in Pakistan.

Twenty-two people were killed in December 2006 when fire broke out at a wedding ceremony in the central town of Jhok Utra. -- AFP