The National Anti-Corruption Commission (NACC) says it will wait for the army's internal probe into alleged irregularities surrounding the construction of Rajabhakti Park in Hua Hin to be concluded before it launches its own investigation.
However, the commission has begun gathering evidence regarding alleged corruption, NACC secretary-general Sansern Poljeak said.
The agency has insufficient information to expand the probe at this time, Mr Sansern said.
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"At the moment, we do not know whether the funds used for the construction of the park came entirely from donations, or if state budget funds were used," he said.
Mr Sansern said he expected this information will be provided by the army committee probing the matter. The prime minister has said previously that as far as he was aware the project was funded by donations, not the public.
It is standard procedure to let government agencies -- in this case the army -- conduct an internal probe before stepping in, he said.
For the case to fall under the NACC's jurisdiction, the corruption accusations would have to involve state officials ranking higher than a C8 administrative level.
"Even in the case of donations, if the foundation is handling those funds in the public interest, use of the fund should be based on state regulations which require correct documentary records," he said.
Mr Sansern said if any state officials are found to be involved in corruption, the anti-graft commission will take necessary steps and launch a full investigation, he said.
If a complaint regarding this matter is filed with the NACC, the watchdog agency will consider the petition and rule on whether it has the authority to set up a panel to look into the case independently of the army's probe results, Mr Sansern said.
Meanwhile, the NACC sub-committee's investigation into allegedly fake government-to-government rice deals with four Chinese companies under the previous Yingluck Shinawatra government has finished.
Results of the probe have not yet been disclosed.