A marine conservationist working with the environmental group Greenpeace says an oil spill off north-eastern China appears much worse than the Chinese government has reported.
Rick Steiner, who has been to see the pollution around the port of Dalian, says that between 60,000 and 90,000 tonnes of oil has gushed into the yellow sea.
"This is certainly the largest oil spill in China's history," he says, "and I do find it ironic that US and China have both had their largest oil spills at the same time. These hidden costs of oil are there whether we see them or not."
China earlier put the spillage at a small fraction of the Greenpeace estimate.
Workers are still struggling to clean up what has been described as the country's worst oil spill, a fortnight after explosions following a depot fire caused crude to leak into the sea for several days.
An army of volunteers and fishermen has been mobilised to help clean up the pollution around Dalian, one of China's most important strategic oil reserves.
But conditions are grim for those involved, the BBC reports: the scene at a small harbour where they are collecting the oil is like something out of the 19th century.
Toxic sludge gathered in jars
Fishermen covered in oil, some of them working in their underwear, scrape up the toxic sludge that spills out of the jars they have brought back from the open sea.
No one is wearing protective goggles, facemasks or even gloves to protect them from the hazardous chemicals in the oil.
It takes them four or five hours to sail back from where they collect the oil on the open sea.
Then they have to wait until nightfall, when the temperature drops and the oil is at its most viscous, to scoop it out.
The government says the slick is under control and has not reached international waters. That is thanks in no small part to the efforts of the fishermen.
