A tanker carrying Iranian oil that collided with a Chinese freight ship in the East China Sea on Saturday was still ablaze on Monday morning, a South Korean coast guard official said as emergency rescue teams continued to search for the missing crew.

The Sanchi tanker run by Iran's top oil shipping operator, collided with the CF Crystal about 160 nautical miles off China’s coast near Shanghai and the mouth of the Yangtze River Delta on Saturday evening.

Chinese state media CCTV showed pictures on Sunday of the tanker ablaze and billowing plumes of thick dark smoke. China sent four rescue ships and three cleaning boats to the site, while South Korea dispatched a ship and a helicopter. The US Navy sent a military aircraft to assist with the search, China Daily reported on Monday. "It was not known if any of the tanker’s missing 32 crew members had been rescued," said the coast guard official, who declined to give his name as he was not authorised to speak to media. He was speaking as of 8 AM Korean time (2300 GMT, Sunday).

The Panama-registered tanker was sailing from Iran to South Korea, carrying 1,36,000 tonnes of condensate, an ultra light crude. That is equivalent to just under 1 million barrels, worth about $60 million, based on global crude oil prices.

Hanwha Total Petrochemical Co Ltd in South Korea was due to receive the cargo and was looking at ways to replace the lost barrels, a spokesman said. “The company may use its own stock, ask Iran for another cargo or seek alternative condensate supplies from Qatar,” he said. It was not affecting operations on Monday, he said.