The Royal Forestry Department (RFD) is working closely with the Agricultural Land Reform Office (Alro) to determine if it can take legal action against Palang Pracharath MP Pareena Kraikupt.
The PPRP MP for Ratchaburi stands accused of illegally acquiring 682 rai of Sor Por Kor land and encroaching on 46 rai of state forest in the province.
The RFD has already filed a complaint against her for forest encroachment.
However, it remains unclear as to which agency has the jurisdiction over the 682-rai plot which was once under the jurisdiction of the RFD before it was later transferred to the Alro to be distributed in 2014 as part of a land-reform programme to provide land to poor farmers. The transfer happened in the period when Ms Pareena's farms were operational.
Thawatchai Ladkrud, the RFD inspector who is leading an inquiry panel into the land controversy, said the panel is studying related laws to see if the department can lodge a fresh complaint against Ms Pareena over the Sor Por Kor plot.
He said one of the laws has to do with a Supreme Court ruling regarding the occupation of a land plot before it was declared Sor Por Kor land. Based on the ruling, Alro can file a complaint because the plot is under its jurisdiction.
He said the panel is also waiting for a legal review of the jurisdiction issue by the Council of State, the government's legal adviser.
"We have to carefully study the laws because the land in question involves two agencies.
"Once who has authority over the land has been determined, legal action will be immediately taken," he said.
Deputy Prime Minister Wissanu Krea-ngam said yesterday the controversy spells out the need for the government to push ahead with the "One Map" project, which is aimed at standardising the maps used by state agencies.
"As the One Map will be based on a common scale, authorities will be better equipped to deal with illegal ownership of Sor Por Kor land-reform plots," he said.
When asked about Ms Pareena's case, the deputy prime minister said that the first thing that needs to be established is which agency has jurisdiction over the land in question and which law is applicable in the case.
Chief opposition whip Sutin Klungsang said yesterday the opposition is closely monitoring the case, before saying that what the government does or does not do could become their political ammunition for launching a censure debate against the administration.