The 34 notes, all bearing a 1973 issue date, have a combined face value of S$340,000 ($267,000).

The casino accepted 28 of them over two visits, exchanging one for chips on June 9 and taking 27 into his casino account on June 12, The Straits Times reported.

The man, identified only as Steven, was stopped by casino security and police on June 26. He was told that serial numbers on some of the six new notes matched those he had exchanged earlier.

He is being investigated for bringing a large sum of undeclared cash into Singapore, circulating counterfeit currency and using counterfeit currency, his Jakarta-based lawyer Yosia Ginting told The Straits Times. The Singapore Police Force confirmed a report had been lodged and said investigations are ongoing.

Steven has surrendered his passport and was told he must stay in Singapore for three to six months, Yosia said. Using counterfeit banknotes in Singapore carries a jail term of up to 20 years.

Differing accounts

"Steven is a victim of fraud and is not part of a counterfeit money ring," Yosia said. He said a man named Anthony, introduced through a friend, gave Steven a single note at a Jakarta cafe on June 8, saying he wanted to exchange it because it was old.

When a money changer in Singapore refused the note because the denomination was too high, a VIP host at RWS suggested the casino, where it was accepted, according to Yosia.

On June 11, Anthony handed over 33 more notes, describing them as an inheritance, the lawyer said. Anthony also said he would buy a shophouse Steven was selling in South Tangerang, near Jakarta, for Rp4.5 billion ($252,000) once Steven brought the money back in smaller bills.

Steven deposited 27 of the notes and kept six in Jakarta, which he used on June 22 toward payment for a house in Pamulang, Banten Province.

When the seller's daughter could not exchange them there, he flew back to Singapore with her and his family on June 26 to change them at the casino.

Dosma Sijabat, another of Steven's lawyers, said on Sept. 22 that three people, identified by the initials HJ, EAK and AN, had asked Steven to exchange the notes for a commission because he had once worked in Singapore.

The three recorded a video promising to take responsibility if the notes proved fake, he said. "We can confirm our client is not the owner of the counterfeit money," Dosma told Tempo.

Saleh Balfas, a lawyer for EAK and AN, told Indonesian news portal detikcom that the notes belonged to HJ and that Steven took a S$500 commission on the first exchange.

Steven then insisted on carrying all 33 remaining notes to Singapore at once, paying a Rp400 million ($22,400) deposit for them, Saleh said.

Steven's wife reported the three to Jakarta police on July 3. The case was later transferred to South Tangerang police, who said on Sept. 16 they had upgraded it from a preliminary inquiry to a formal investigation.

Singapore first issued the S$10,000 note in 1973 and stopped issuing it in 2014, citing money laundering risks.

Existing notes remain legal tender, but banks stopped recirculating them the same year, according to the Monetary Authority of Singapore.