Tongans have been warned that a business operation called WorldVenture is a pyramid scheme and that people participate at their own risk.
The National Reserve Bank of Tonga said WorldVenture was clearly a multi-level marketing company that encouraged people to recruit more members.
The bank said it had become aware that the company had received support in the Tongan community.
Pyramid schemes are unsustainable business models and are illegal under the country's Financial Institutions Act, the bank said.