At least 11 people were killed and 59 wounded Tuesday when a gas cylinder exploded and started a fire inside an oil tanker being broken up for scrap in southwestern Pakistan, officials said.
The accident occurred at the Gadani ship-breaking yard in the southwestern province of Balochistan, some 50 kilometres (30 miles) west of Karachi.
"A gas cylinder explosion caused a huge fire in the ship which was being dismantled," Balochistan Home Secretary Akbar Harifal said, ruling out a deliberate attack.
"We have recovered at least 11 bodies so far and shifted 59 injured to Karachi," said Zulfiqar Ali Shah, the deputy commissioner of the area.
"All the injured had severe burns," he further said.
The state-run Radio Pakistan website and other local news channels put the death toll at 17.
TV footage showed a thick plume of black smoke rising from the ship, as local rescue workers rushed to the scene. It was not clear what caused the blast.
Nasir Mansoor, a representative of the National Trade Union Federation of Pakistan, said the explosion was so big it blasted pieces of metal two kilometres (one mile) away.
Another leader of a ship-breaking workers union said a big explosion and fire engulfed the vessel moored in Gaddani.
"Things are really bad here," union president Basheer Mehmoodani said. "There's an unclear number of workers said to be trapped in the burning ship."
Firefighters were called from Karachi but they proved ineffective given the size of the blaze, he said.
Safety and environmental regulations exist in Pakistan, but they are seldom enforced. Ship-breaking companies are supposed to provide protective equipment like helmets and gloves, and arrange for the safe handling of toxic materials.
Industrial accidents are common in Pakistan with workplaces often forgoing basic safety measures and equipment in the absence of legislation to protect labourers.
Historically, ships were broken down at home bases where they were built, before high costs and safety and environmental laws drove the business to less strict developing countries.
Each year around 800 ships are sent to breaking yards, with about 80 percent ending up on South Asian maritime graveyards like Gaddani, according to Ship-breaking Platform, a non-governmental coalition of human rights organisations.