The Department of Special Investigation (DSI) insists an investigation report looking into the practices of Akara Resources Plc -- a gold mining company operating in the northern region -- has not "disappeared".
A group, the Civic Group for Reform of Resources and Gold, on Thursday handed a petition to the DSI about the matter.
A DSI probe in August 2018 said the company's large mine may have encroached on parts of a forest and highways in tambon Khao Chet Luk in Phichit's Thap Khlo district and tambon Thai Dong in Wang Pong district of Phetchabun.
The group previously petitioned Prime Minister Prayut Chan-o-cha to appoint Vicha Mahakun, former member of the National Anti-Corruption Commission, to look into the case. Wanpen Promrangsan, from the group, said it wants Mr Vicha to prevent any interference in the DSI probe.
Pol Lt Col Supat Thamthanarug, deputy director-general of the DSI, said the agency has forwarded Akara Resources' case to public prosecutors. Nothing was missing from the case dossier, he said.
Earlier this year, the group also lodged a complaint with the DSI accusing the company of using proxy shareholders, operating a mine beyond its licensed zone, discharging hazardous substances into the environment and having questionable financial transaction and tax payment issues.
On Feb 25, the DSI set up a committee to review the accusations made by the group before deciding to take up the case.
In 2016, Gen Prayut, then head of the ruling National Council for Peace and Order, invoked Section 44 of the military government's interim charter to suspend mining operations.
He cited villager complaints that waste discharged from Akara Resources' mine had poisoned the environment and harmed their health.