A tanker carrying $60m worth of oil is on fire off the coast of China after a colliding with another vessel.
The 32 crew of the Iranian tanker Sanchi are missing while the 21-strong crew of the other cargo vessel have been rescued.
The incident occurred late on Saturday evening around 300km off the coast of Shanghai as it was heading for Daesan in South Korea from Kharg Island in Iran.
"Sanchi is floating and burning as of now. There is an oil slick and we are pushing forward with rescue efforts," the Chinese transport ministry said, according to Reuters.
The implications of the spill are as yet unclear and authorities from both China and South Korea are involved in rescue efforts.
The tanker, registered in Panama and manage by the National Iranian Tanker Co (NITC), was carrying 136,000 tonnes of condensate, an ultra-light crude, the equivalent of around one million barrels.
The last major oil spill was in 2002 when the Prestige of Spain sank of the coast of Spain, leaking 63,000 tonnes of oil into the Atlantic and creating one of Europe's worst ecological disasters.