About 50 people said they collectively invested more than $1 million in Ufun, a regional investment scheme that is now the subject of police investigations in Thailand, reported Chinese-language evening daily Shin Min Daily News.

In May 2015, four people allegedly linked to Ufun were arrested in Bangkok over allegations of running a pyramid scam and money laundering.

They are believed to have smuggled about $31 million into Malaysia for money laundering, Thailand's The Nation newspaper reported at the time.

Ufun's business straddles Singapore, Malaysia and Thailand, and according to websites linked to the firm, members may earn commissions for referring new members to the platform.

A business manager in the IT sector, who wanted to be known only as Mr Tan, said he had purchased digital currency called "Utokens" from the firm.

Members like Mr Tan were allegedly told that the currency could be used to buy merchandise online or even invest in property.

Mr Tan, 44, said he invested almost $45,000 from August to November 2014 after attending a presentation by the firm.

Over four months in 2014, he put in sums of US$1,000 and US$5,000 several times, totalling US$31,000. This amounted to $44,950 at the prevailing exchange rate then.

Mr Tan said he received about $10,000 in returns from September 2014 to May 2015, but stopped receiving payments after the arrests.

He said Ufun executive chairman Daniel Tay released YouTube video clips after the Bangkok arrests to say that Ufun was not a pyramid scheme.

A pyramid scheme is structured to funnel the money put in by newly recruited investors to those who joined the scheme earlier.

Mr Tan said the video helped allay his fears but when he did not receive anything after the arrests right up to the end of last year, he felt uneasy and made a police report.

Police told Shin Min that investigations are ongoing.

Mr Tan has since engaged a debt collection firm that said it is in negotiations with Ufun's Singapore unit.