There are fears of an environmental disaster in the East China Sea as a tanker continues leaking oil two days after colliding with a cargo ship.
Chinese officials have told state media the Sanchi is in danger of exploding and sinking.
Rescuers trying to reach the burning tanker were beaten back by toxic clouds, the transport ministry says.
The body of one crewman, among the 30 Iranians and two Bangladeshis on board, has been found. The rest are missing.
The Panama-flagged Sanchi was bringing its cargo of oil from Iran to South Korea when it collided with the Hong Kong-registered freighter CF Crystal, carrying grain from the US, in the East China Sea. The incident occurred about 260km (160 miles) off the coast of Shanghai.
The collision, in the mouth of the Yangtze River Delta, occurred on Saturday evening.
The exact cause of the collision is not yet known.
The tanker, run by Iran's leading oil shipping operator, has on board 136,000 tonnes of condensate, which is an ultra-light version of crude oil.
That is about one million barrels and at current prices is worth roughly $60m (£44m).
The Sanchi will also be carrying a certain amount of heavy - and toxic - shipping fuel.
Condensate is very different from the black crude that is often seen in oil spills.
It exists in gas form within high-pressure oil reservoirs and liquefies once extracted.
It is highly toxic, low in density and considerably more explosive than regular crude oil.
Condensate, which does not need the heavy refining process of denser crude, creates products such as jet fuel, petrol, diesel and heating fuel.
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