A local conservation group in Songkhla is trying to build up public support against the navy's plan to build a radar base in the compound of Khao Daeng, an ancient city with archaeological significance.
Suebsakul Srisook, director of Songkhla Heritage Trust, sounded the alarm when he posted about the navy's project in Khao Daeng on his Facebook page, saying it is a threat to the province's plan to nominate Muang Songkhla as a World Heritage site.
Mr Suebsakul said Khao Daeng is an ancient city that dates back some 400 years to the Ayutthaya period.
On the mountain top are twin pagodas that showcase a multicultural community, as well as other provincial attractions including arts, heritage architecture and natural sites, he said.
Once listed as a World Heritage site, Songkhla is hoped to pull in 12 million visitors a year. Those visitors may also frequent another heritage site in Malaysia's Penang, which is not too far from the southern border, said Mr Suebsakul.
Once Khao Daeng is recognised, Songkhla will become a tourism hub for the southern border provinces and bring about comprehensive development in the region, he said.
Describing the navy's radar base project as an "alien" object, Mr Suebsakul said that if construction goes ahead, it will ruin any chance of Songkhla being recognised as a World Heritage site.
"Unesco has agreed to send its staff here to advise us on the listing proposal. But the proposal will surely be as good as buried if and when the radar base is set up in the compound," he said.
Mr Suebsakul has asked the public to join the Songkhla Heritage Trust's campaign calling on the navy to find a more suitable location for radar, adding a separate petition will be submitted to the Fine Arts Department.