Pressure is mounting on the army after graft watchdogs signalled they would start an external investigation into the one-billion-baht Rajabhakti Park project.
A source at the National Anti-Corruption Commission (NACC) said the agency is set to discuss the matter at its regular meeting on Tuesday.
NACC secretary-general Sansern Poljeak has been gathering facts on the park for the last two weeks.
The NACC has decided to act despite there being no complaint seeking an inquiry into the alleged irregularities surrounding the park project.
The NACC source said the future of any investigation rests on the evidence Mr Sansern presents in the meeting.
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Mr Sansern said Monday the NACC is authorised to investigate the park scandal for abuse of authority by state officials despite no complaint being filed.
He said the agency is reviewing information about the foundation running the park before it decides whether it is authorised to scrutinise the spending of donation money.
Meanwhile, the Anti-Corruption Organisation of Thailand (ACT) will write to the army Tuesday, urging it to let external bodies examine details of the construction of Rajabhakti Park.
Over the weekend, ACT secretary-general Mana Nimitmongkol said the alleged irregularities surrounding the project should not be overlooked, even though an internal probe by the army found no wrongdoing.
Too little information has been released to the public, Mr Mana said.
Several questions regarding the costs of palm trees, expensive banquet seats and commission fees related to the building of giant statues are still unanswered, he added.
ACT chairman Pramon Suthiwong said Monday that Mr Mana's views on the park were shared by other members of the organisation.
"Agencies whose role covers investigating graft accusations should be allowed to perform their duty," he said.
Army commander Theerachai Nakvanich said in a press briefing last week that the army's inquiry committee had wrapped up its investigation and found no corruption.
As a result, there was no need for other agencies, including the NACC, to investigate the case, he said.
However, also on Monday, Deputy Prime Minister Prawit Wongsuwon said the NACC is welcome to probe the Rajabhakti Park project if there are grounds for an investigation.
He said the NACC should feel free to delve into the scheme which will help clear up any suspicions about the scandal.
Gen Prawit, however, said there is no need for Deputy Defence Minister Udomdej Sitabutr, who serves as chairman of the Rajabhakti Park Foundation, to clarify anything to the press.
Gen Theerachai last week distanced himself from allegations of "commission payments" in the project, saying reporters need to ask Gen Udomdej about the issue.
Gen Prawit said the park foundation has so far done nothing and the park project has been handled by the army.
"No press briefing is needed. Let the army handle the issue [regarding the press]," he said.
The Rajabhakti Park project was launched by Gen Udomdej when he was the army chief.
The Rajabhakti Park Foundation was set up to manage the park, with donations from private businesses and the public sought to finance the project.
After the scandal emerged, Gen Udomdej admitted an amulet trader had demanded "commission fees" from the foundries.
An army officer later visited the foundries to return the money, but they "volunteered" to donate the money back to the army.
Meanwhile, police believe two former policemen are linked to the alleged criminal network of former lese majeste suspect, the late fortune teller Suriyan Sucharitpolwong, but they don't have enough evidence yet to issue arrest warrants.
Suriyan died while in army custody.
The pair were among eight officers transferred to inactive posts when the lese majeste scandal surfaced.
Police spokesman Pol Maj Gen Piyapan Pingmuang said five of the lese majeste cases against the Suriyan network are expected to be submitted to prosecutors next week.
Officers are still hunting for Col Khachachart Boondee, who faces an arrest warrant for his role in the lese majeste network, he added.
