HONG KONG — Hong Kong’s central bank has warned against investing in virtual currencies, amid local media reports that a Bitcoin exchange may have run off with $387 million in client funds in what could be the biggest Bitcoin scandal after last year’s bankruptcy at the Mt. Gox exchange, based in Tokyo.

The South China Morning Post reported on Monday that clients of the MyCoin exchange, based in Hong Kong, had approached a local lawmaker, saying the company had absconded with their money. An assistant for Legislative Council member Leung Yiu-chung said that Mr. Leung had received more than 15 complaints from MyCoin clients regarding the allegations and that these would be passed on to the police on Wednesday.

The Hong Kong Monetary Authority said in a statement late Monday that the case “may involve fraud or pyramid schemes,” adding: “Given the highly speculative nature of Bitcoin, we have all along urged the public to exercise extra caution when considering making transactions or investments with Bitcoin.”

Calls to MyCoin in Hong Kong could not be connected. Calls to the company’s China customer service line were not answered.