China is boosting effort to clean up a major oil slick off its north-east coast, following a pipeline explosion.
There are growing fears that strong winds have dispersed the pollution more widely than previously thought.
The environmental group Greenpeace told the BBC the oil was up to 20cm thick along parts of the coast near the city of Dalian.
Shipments of oil from the north to the industrial belt in the south have been disrupted since the accident.
At least one person has died during the clean-up operation, after being thrown from a ship by waves and drowning in the oil.
The oil spilled into the sea in north-east China after two pipelines exploded on Friday night, resulting in a fierce fire.
Officials say an area of ocean covering 430 sq km (165 sq miles) is now polluted - oil-eating bacteria and oil-skimming vessels are being deployed to remove the slick, which Greenpeace says is China's worst in recent memory.
Zhong Yu of Greenpeace told the BBC's Chinese service there was a heavy layer of oil covering the coastline.
"In some places, the oil has been treated, so it is a thin layer. But because it is quite light, it is very easy to spread," she said.
"The air quality in where I am staying is not good; if you go nearer to where the accident happened, you smell something acid in the air, and within 2km of radius of the disaster, the smell of petrol is very strong."
An official in the State Oceanic Administration told Chinese official media that heavy winds on Monday had broken up the spill and dispersed it more widely than had previously been reported.
The BBC's Chris Hogg in Shanghai says oil shipments from the port of Dalian in north-east China, where the pipelines exploded, have slowed.
Usually, 30,000 to 50,000 tonnes of oil for use in factories in the south leave the port each day.
Reserves in the south are reported to be ample at present - enough to guarantee 10 days' supply - and the oil price in that part of the country is stable.
But the officials leading the clean-up warn it could take at least that long to complete their work.
Some reports suggest the winds since Monday have started blowing the oil back towards the shore away from international waters.
That could make the clean-up easier, but the environmental impact worse if the oil contaminates more of the coastline, says our correspondent.
Every year fishing boats in the area stop fishing from June to August.
Some of their skippers are worried that when they put to sea again in a few weeks, the pollution will have ruined the fishing grounds.