Starting in July, the government will ban fishing, fish feeding, anchoring on coral reefs, construction on the beach, and walking on the seabed on the islands, said Jatuporn Burutphat, director of the Department of Marine and Coastal Resources on Friday.

The islands include Koh Samui, Koh Tao and Koh Phangan. Koh Phangan is known internationally for its regular Full Moon Parties and is visited by almost one million tourists a year, while Koh Samui welcomed more than 2.3 million tourists in 2016.

Thailand's booming tourism industry, which accounts for up to 20 per cent of the country's gross domestic product (GDP), is seeing a continuous rise in the number of tourists each year. The Ministry of Tourism and Sports has projected that 37.5 million tourists will visit Thailand in 2018, up from last year's figure of 35.3 million.

"The amount of garbage and waste water on these islands is so big that it will become unbearable in the near future, and we have to think about the future," said Jatuporn.

People found violating the bans can face up to one year in prison and a fine of 100,000 baht (3,205 dollars), he said. Smoking has also been banned on 24 beaches nationwide since February due to huge amounts of cigarette butts.

is/ch (dpa)