The Department of National Parks, Wildlife and Plant Conservation wants legal action taken against luxury resort operators accused of encroaching on Sirinart National Park in Phuket.
The department has sought help from the Anti-Money Laundering Office (Amlo) and the Department of Special Investigation (DSI).
National parks department chief Manophat Huamuangkaew said he had been forced to approach Amlo and the DSI because local police had been dragging their feet over the forest encroachment cases against 11 resorts.
The alleged encroached area covers around 600 rai of land.
Although forestry officials had evidence of suspected national park encroachment by the resort operators, Phuket police handling the case had refused to forward the case to prosecutors, reasoning that the resort owners could present land deed documents to the police.
Mr Manophat yesterday insisted the land title deeds were illegally obtained. He also questioned the Phuket police's failure to investigate the alleged illegal issuance of the deeds.
"We have clear evidence from satellite images that all 11 resorts are encroaching on protected forest. The satellite images show the forest areas were not used or farmed before they were declared part of the national park in 1981," he said.
Forestry officials believe local police are under pressure from influential figures involved in the case.
"I believe the case will make significant progress with the DSI and Amlo's interventions," Mr Manophat said, adding that the two agencies had already agreed to look into the case.
Mr Manophat quoted an Amlo investigator as saying an initial probe had found businessmen and politicians were involved in the Sirinart National Park case.