Piyamarn Techapaibul, president of the Tourism Council of Thailand, said the damage could have been worse if the rupture occurred during the high season, but an impact assessment on the environment and other aspects must be conducted later.
She said Thailand has experienced nine oil spills in the last decade, indicating that such an incident should not happen too often.
Piyamarn called for clear explanations on the responsibilities of state agencies concerned in coping with the spill and prevention measures.
Tourism entrepreneurs in Surat Thani where an oil drilling platform is located off the coast have also expressed concern and sought assurances on safety measures.
Ao Prao on Samet Island has been severely hit by the oil slick but the tourism business at other beaches in Rayong has remained unaffected, according to the Tourism Business Association in Rayong.