The National Anti-Corruption Commission (NACC) has begun an inquiry into the 33-million-baht contract for a nameplate and logo redesign of Bang Sue Grand Station, a project criticised for being costly and possibly using questionable methods for hiring a contractor.
Niwat Kasemmongkok, the NACC secretary-general, said the commission was gathering the information it needs.
The anti-graft agency was interested in finding out about the procurement process and what criteria were adopted for hiring the contractor, he said.
The NACC is authorised to investigate if bid rigging was at play or if any state officials connected to the state project had abused their power by illegally approving concessions to a private firm, Mr Niwat said.
The State Railway of Thailand (SRT) signed the contract with Unique Engineering and Construction Plc (Uniq) for the redesign project, which includes the installation of two SRT logos as well as 48 three-metre-tall Thai letters and 62 English letters.
The SRT labour union said it thought the cost was quite high and demanded a probe on the bidding.
The Transport Ministry has also launched an investigation which began on Monday.
The redesign follows His Majesty the King renaming the Grand Station "Krung Thep Abhiwat Central Terminal" in September.
Mr Niwat added the cost-effectiveness of the project will come under the scrutiny of the State Audit Office.
He said, however, that if the contact complied with proper regulations even though the project was deemed non-urgent or non-essential, the NACC might not be able to seek to prosecute any party.
Meanwhile, the SRT spoke out on Wednesday, insisting the project was above board.
The agency said it established a committee to draft the scope of the work and set the median price for the project.
The reason the so-called "specific" method of bidding was adopted was due to the urgency in implementing the project.
Nonetheless, it adheres strictly to the Comptroller General's Department's procurement regulations, it said.
The contract involves not only the installation of a new nameplate but also removal of the old one.