The Natural Resources and Environment Ministry has decided to include the Pa Kaoruak and Pa Khao Maung National Reserve Forest in Phuket in the ongoing "One Map" project.
This goes against an earlier decision by the Department of Royal Forest.
The reserve forest has unclear boundaries and the department had earlier agreed to keep them out of the project that will force all state agencies in Thailand to use "One Map", utilising a more detailed scale ratio of 1:4,000. Currently, official agencies use different scales such as 1:50,000 resulting in overlapping and conflicting boundaries on maps.
These maps are also used to determine cases of forest land encroachment.
Kasemsun Chinavaso, permanent secretary for natural resources and the environment, said the ministry will set up a committee chaired by himself to verify the correct forest boundary of the controversial national reserve forest within three weeks.
It will then become one of 1,221 national reserve forests which are being prepared for inclusion in the "One Map" project. Map experts from the army will be on the committee, he said.
He said there was a "misunderstanding" over forest boundaries as people plotted them using different scales, and the newly-established committee will set clear and correct boundaries.
"We would like to ensure that not one inch of reserve forest land will be lost. We have 193 landmark points in the national reserve forest that we will use to identify the correct boundaries," he said.
Damrong Pidech, leader of Thai Forest Land Reclamation Party, had previously voiced his concern that if the Department of Royal Forest submitted wrong forest boundaries, the country would lose over 1,200 rai of forest land in Sirinat National Park, which includes the Pa Kaoruak and Pa Khao Maung National Reserve Forest, and it would benefit people who illegally possess land there.
He said he will closely monitor the ministry's work and if something goes amiss, he will take legal action against wrongdoers.
He warned the "One Map" project might create a loophole that officials will use to "include" or "exclude" forest zones if they have not stuck to the boundaries declared by law as there is a clause stating that any forest land subject to dispute must be settled by discussion among officials concerned.
Mr Kasemsun insisted the way to set forest boundaries at other national reserve forests was by surveys on foot to mark GPS coordinates at significant landmarks. The process includes local participation to gain acceptance in the event of land encroachment or disputes.
Chonlatid Surasawadi, chief of the Department of Royal Forest, said he decided to withdraw the controversial national reserve forest from the project as the boundary was still not clear. But if the permanent secretary wanted to include it, he has no problem.
He said the department in 2012 set up a committee to re-verify the forest boundary as there was an attempt to issue land documents in the national reserve forest zone. Later in 2014, a new committee was set up to verify the boundary set by the previous panel. The department asked the Department of National Parks, Wildlife and Plant Conservation to verify the forest boundary but got no answer.