Thirty-two crew members are missing after an oil tanker collided with a freighter off China's east coast, state media reports.
An official in Iran's Oil Ministry, who spoke to The Associated Press on condition of anonymity because he was not authorized to speak to reporters, said 30 of the tanker's 32 crew members were Iranians.
"There is a wide perimeter of flames around the vessel because of the spillage and search and rescue efforts are being carried out with difficulty", Iran's Rastad said.
The 21-strong crew aboard the Hong Kong-registered CF Crystal have all been rescued and the ship was not severely damaged. That is equivalent to just under 1 million barrels, worth about $60 million, based on global crude oil prices.
The official said the tanker was owned by the National Iranian Tanker Co. and had been rented by a South Korean company, Hanwha Total Co.More news: Bigg Boss 11: Bandgi Kalra to feature in a Bollywood film?
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He further said that the tanker was leased by a South Korean company.
"The Sanchi is still floating and continues to burn, there is oil on the sea surface; search and rescue operations are rushing and underway", the ministry said in a statement. "There is an oil slick and we are pushing forward with rescue efforts". China sent four rescue ships and three cleaning boats to the site, while South Korea dispatched a ship and a helicopter.
The 274-meter-long tanker was still ablaze on Sunday and images on Chinese television showed huge clouds of smoke rising from the stricken vessel.
Shipping experts said the incident could potentially disrupt shipping in and around Shanghai, one of the world's largest and busiest ports.
It was not clear, however, whether the tanker was still spilling oil.