CONCERN over the deteriorating environment of popular Koh Samet has prompted Thai authorities to ban tourists indefinitely. Tourists have been prohibited from the east coast island for 12 months and there is no sign of the ban being lifted in the near future. ''Although the government is trying to increase the number of tourists [to Thailand] it is increasingly concerned about protecting the environment,'' said a spokesman for the Tourism Authority of Thailand in Hong Kong. He said the government was particularly concerned about water pollution around the island which, together with nearby islands Kudi Kruai Khan and Plai Tin, was proclaimed a national park in 1981. In recent years, Samet's beautiful beaches, clear waters, inexpensive bungalow accommodation and excellent food, have become increasingly popular among travellers looking for unspoiled tropical beauty. The ban on tourists is not the first to be introduced there. However, pressure from the local tourism industry has always resulted in it being re-opened. But, until the present ban is lifted, the only way to see the area is to take a boating or fishing trip around the island. Inexpensive boat and fishing trips are offered by the Thana-Pong Patthana Business Co from its base at the nearby fishing centre of Rayong.