A unit of the South African Police Service said it has started an investigation into an alleged cryptocurrency investment fraud that has affected more than 28,000 people and led to losses of more than one billion rand ($80.4 million).

The allegations involve “BitCaw Trading Company, commonly known as BTC Global,” the police unit said in an emailed statement on Friday. “Members of the public are believed to have been targeted as part of the scam and encouraged by BTC Global agents to invest with promises of 2% interest per day, 14% per week and ultimately 50% per month,” Bloomberg reported.

“BitCaw Trading was not involved in the BTC Global scam and we are shocked to see our name connected with it,” Andrew Caw, who set up BitCaw Trading, said in messages via Facebook on Friday. “BitCaw Trading assists people with buying and selling Bitcoin as well as other Bitcoin related services. We do not manage third-party money or offer any kind of investment” and BitCaw didn’t set up BTC Global, he said.

BTC Global’s services are suspended, according to that company’s website. In a statement on the site it blames its financial woes on a former employee. No contact details are given for BTC Global.

“We are as shocked and angry as everyone,” the BTC Global team said in the statement. “If you feel you’ve had a crime committed against you, you need to follow the legal procedures to deal with the matter.”

Bitcoin prices have declined 45% this year and 58% since the high of $19,511 reached on Dec. 18. It was 0.9% lower at $7,485 in New York.

South Africa’s central bank chooses to call digital currencies such as Bitcoin “cyber-tokens” because they don’t meet the requirements to be classified as money.

“We don’t use the term ‘cryptocurrency’ because it doesn’t meet the requirements of money in the economic sense of the stable means of exchange, a unit of measure and a stable unit of value,” Reserve Bank Deputy Governor Francois Groepe told reporters in Pretoria on Thursday. “We prefer to use the word ‘cyber-token’.”

Digital currencies such as Bitcoin and Ethereum are becoming increasingly popular, with regulators in some countries struggling to move fast enough to manage them. The reserve bank has established a financial-technology, or fintech, unit to review its position on private cryptocurrencies and to help draw up an appropriate policy framework and regulatory regime.