The commission plans to soon file a lawsuit at the Central Criminal Court for Corruption and Misconduct Cases.
The group of government officials and businesses allegedly used a document called Sor Kor 1 to appropriate title deeds for 1,755 rai (281 hectares) land worth 30 billion baht since 2004.
The encroachment later expanded to 2,743 rai worth over 50 billion baht after 2011.
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Kittipat Tharapiban, the former national park chief, said once the legal procedures are completed, they will repair the ecosystem and allow citizens to use the Sirinat beach area.
"We have prepared 6,000 whistling pine tree sprouts to revive the ecosystem at the beach," he said.