The Sanchi tanker, registered in Panama, collided with the CF Crystal about 160 nautical miles off the coast near Shanghai on Saturday, the Ministry of Transportation said in statement.
The tanker's 32 crew members were missing.
It was sailing from Iran to South Korea, carrying 136,000 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.
"Sanchi is floating and burning as of now," the ministry said. "There is an oil slick and we are pushing forward with rescue efforts."
It had sent four rescue ships and three cleaning boats to site by 9 a.m. (0100 GMT), it added.
South Korea has also sent a ship and helicopter to help. A Korean Coast Guard official confirmed the tanker was still on fire at 1 p.m. (0500 GMT). He declined to be identified as he was not authorised to speak to the media.
State media CCTV showed pictures of the tanker ablaze and billowing plumes of thick dark smoke.
The Chinese government gave no details of the size of the spill. The Foreign Ministry said in a separate statement the cause of the incident was under investigation.
Reuters ship tracking data shows Sanchi was built in 2008 and was managed by the National Iranian Tanker Co (NITC). Its registered owner is Bright Shipping Ltd.
The Sanchi tanker, leased by Hanwha Total Petrochemical Co Ltd, had "valid foreign insurance", Iranian oil ministry spokesman Kasra Nouri told Iran's state television.
Hanwha Total was not immediately available for comment.
Sanchi collided with CF Crystal, registered in Hong Kong, which was carrying 64,000 tonnes of grain from the United States to China's southern province of Guangdong, the government said.
CF Crystal's 21 crew members, all Chinese nationals, have been rescued. It was due to arrive on Jan. 10, according to Reuters ship tracking data.
CF Crystal, which was built in 2011, suffered "non-critical" damage, China's transport ministry said.
The incident marked the first major maritime incident involving an Iranian tanker since the lifting of international sanctions on Iran in January 2016.
There was a collision involving an NITC-operated supertanker in the Singapore Strait in August 2016, but there was no loss of life or pollution.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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