Thai naval vessels have joined efforts to stop hundreds of barrels of oil from a pipeline leak in the Gulf of Thailand reaching the kingdom's beaches.
About 50,000 litres of crude oil spilled into the sea on Saturday about 20 kilometres off the coast of the eastern province of Rayong, operator PTT Global Chemical said.
The company, part of state-owned giant PTT, said 10 ships were involved in an urgent clean-up and it was confident of containing the leak.
"The aerial photos taken on Sunday show that the area of the spill was reduced," the company said, estimating up to 20,000 litres had been cleaned up.
But there were also fears about the effect of the chemicals used to disperse the crude oil.
"We still have some concern about the chemical being used, even though it is clear that the oil leak will not reach the beaches or coral," said Phuchong Saritsadeechaikol, director of the government's Marine and Coastal Resource Conservation Centre.
Another PTT subsidiary was involved in a huge oil spill off northwestern Australia in 2009 that was the country's worst ever offshore drilling accident.
The slick from the Montara oil field spread as far as Indonesian waters and grew to almost 90,000 square kilometres.