Favourable wind and sea conditions kept an oil slick away from beaches in eastern Thailand on Sunday, according to authorities, but concerns remain that the spillage may yet strike a popular resort island.

Emergency workers in protective gear removed contaminated sand from the Mae Ramphueng beach in Rayong province, south-east of Bangkok, which was shut on Saturday.

Between 20 and 50 tons of oil are estimated to have leaked into the Gulf of Thailand on Tuesday night from an undersea hose used to load tankers at an offshore mooring point owned by the Star Petroleum Refining Co.

The leak was stopped within hours, the company said.

Most of the oil slick was being pushed toward Koh Samet, a popular tourist island which, along with the rest of the country, is just beginning to recover from the coronavirus slump.

Natural Resources and Environment Minister Varawut Silpa-archa said authorities are taking steps to prevent it hitting the beaches there.

Aircraft have been dropping chemicals to disperse the oil and deploying floating booms to trap it so that it can be skimmed from the surface and removed.

“I am very confident that for one we will be able to prevent the majority of the oil spill to ruin our natural resources, especially the corals,” Mr Varawut told the Associated Press after surveying the Rayong beach.

“Of course some of the corals will be damaged but the majority of it we will be able to save and we will be able to minimise the effects on the people.”

The beachside area is largely dependent on tourists. It has been suffering from the pandemic that has kept visitors away, and the spill will make recovery harder.

The local fishing industry has also been affected by the pollution.

Asked how long until he could declare the disaster over, Mr Varawut said “visually it should be over within a week but environmentally it would last years”.