Authorities say Peter Henderson (57) and Louis Henderson (54) operated a Durban-based entity called Forex International between 2002 and 2003.

They say the pair took money from investors, despite not being registered to do so.

The brothers are said to have lost some of the money offshore, while they spent some of it on themselves.

National Prosecution Authority KZN spokesperson Natasha Kara says they were arrested following an investigation by the Reserve Bank.

She says 18 investors gave evidence in the case.

"Two brothers were sentenced to 15 years imprisonment and 12 years imprisonment respectively in the Durban Specialised Commercial Crimes Court last week after they were convicted of fraud amounting to about R4.6 million, theft amounting to about R1.6 million, reckless and negligent trading and contravention of Section 11 of the Banks Act of 1990.

"One of them was further convicted for failing to comply with a reserve bank instruction."