Some 20-50 tons of oil are estimated to have leaked Tuesday night in the Gulf of Thailand 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, but efforts to keep an oil slick from reaching the Mae Ramphueng beach in Rayong province southeast of Bangkok were unsuccessful, and some oil began spilling onto the sand there on Saturday morning.