National parks chief Chaiwat Limlikhit-aksorn has expressed concern about an increase in land bought on Koh Chang in Trat province by investors with suspected links to shady businesses.
Mr Chaiwat said private investors have bought large areas of land from locals.
"Some investors are alleged to have links with shady businesses," Mr Chaiwat said. "The government and local officials must keep an eye on them."
He said large firms have been expanding their businesses on the island, affecting local enterprises which are gradually fading away. "Local consumers are turning to goods and services and modern conveniences offered by big businesses," he said.
He said modern technologies and satellite images are used to monitor and deter land encroachment.
With development and tourism increasing on the island, it is also important for residents and businesses to retain cultural uniqueness and local identity to boost appeal to tourists, he said.
Koh Chang, or "Elephant Island" because of its elephant-like shape, is Thailand's third largest island after Phuket and Samui. It is located about 300km east of Bangkok, in Trat province, in the Gulf of Thailand.
