The army denies any links to an alleged conwoman who says she is the half-sister of another alleged fraudster Monta "Ying Kai" Yokrattanakan.
Kamonthat Thanathornkhositjira, 62, also known as Kim-eng Sae Tia , or Tum, on Friday was arrested on charges of fraud and falsifying documents with alleged links to lese majeste offences.
She stands accused of invoking the royal institution in a fund-raising scam that swindled more than 3 million baht from victims, after her involvement in a TV programme celebrating the royal institution that was filmed at the army club in Ratchaburi.
Before the programme aired, a press conference was held at the club in June to announce the cast, in which Ms Kamonthat appeared alongside an army major general and an army colonel.
Yesterday, army spokesman Winthai Suvaree said the programme-makers had requested the use of the army club, which is available for public hire, and the army had no involvement in the scam.
Mr Winthai said the army was notified that one of its personnel had joined the June press conference, after the officer in question was invited to appear on the TV show.
A police source said investigators were trying to identify who produced the programme and will summon them for questioning once they find out.
Police are also trying to find out whether senior officials had colluded with Ms Kamonthat to defraud people by citing the royal institution.
So far, police have found a former palace official, sacked nine years ago for committing extortion, was part of the criminal gang.
Prior to Ms Kamonthat's arrest, a police search of her house found valuable items, including antique porcelain, ivory tusks, and commemorative coins bearing royal emblems.
Her half-sister,"Ying Kai", is currently in a remand prison on charges of lodging false complaints, human trafficking, defamation and lese majeste.