An aircraft from a company specialising in recoveries from oil spills has arrived from Malaysia to join an urgent effort to clean up an oil slick before it could hit beaches in eastern Thailand, officials said.

The C-130 joined other planes, ships and a helicopter deployed by the Thai navy to contain the damage from the Star Petroleum Refining Public Company’s oil that leaked Tuesday night from a mooring station in the Gulf of Thailand.

Information from Thailand’s Geo-Informatics and Space Technology Development Agency suggested that prevailing winds could blow the oil slick to major beaches in Rayong province or Samet Island by Friday evening if not cleaned up before then, said Thai navy’s Rear Adm. Wichanu Thupa-ang.

He said the agency’s report estimated that the slick covered 11.65 square kilometers (4.5 square miles).

Star Petroleum Refining estimated that a total of 20-50 tons of oil had been spilled. It said in a statement that the amount of oil in the slick has been reduced to 5.3 tons since dispersant sprays were deployed by aircraft Wednesday. Some initial estimates of the amount of spilled oil were much higher.

Star Petroleum said specialists from the company Oil Spill Response Ltd arrived with the C-130 aircraft.

Wichanu said the largest part of the oil slick would be contained by booms within an area marked by buoys and then sucked by skimmers into holding tanks and properly disposed of.

At the same time, the oil headed toward the beach would also be contained and redirected to the open sea, he said.

Pornsri Sutthanarak, deputy director-general of the Marine and Coastal Resources Department, said that if the oil reaches the coast, it might affect 59 acres of coral and 118 acres of seagrass, causing environmental damage that would take time to rehabilitate.

A photo released by the Royal Thai Navy, an aerial view from a navy plane shows the oil spill off the coast of Rayong on Thursday, January 27th.