TOKYO -- Japan's Financial Service Agency will issue its first warning under the revised payment services law to an unregistered cryptocurrency exchange operator, The Nikkei has learned.

The warning will be issued to Blockchain Laboratory, based in Macau. The agency has decided the company's activities could cause investors to incur losses. The FSA will work with the police and the Consumer Affairs Agency to bring criminal charges if the company fails to respond to the warning.

The move is part of the FSA's more aggressive scrutiny of the activities of unregistered operators in Japan. The revised law prohibits such unregistered exchanges from operating and soliciting in the country.

Blockchain Laboratory operates as an initial coin offering agency to raise funds using cryptocurrencies. It has been offering seminars to lure investors. The law, revised in April 2017, allows only registered operators, or those that have applied for registration, to operate in Japan.

The FSA has repeatedly advised Blockchain Laboratory to halt its business activities in Japan, without success. The FSA will thus warn the company directly, and name it on the FSA's home page. If the operator still fails to comply, the FSA will file criminal charges, and the law enforcement authorities will likely take action, officials said.

Investment in cryptocurrencies has risen sharply since 2017, coinciding with a surge in market values. Officials say some non-registered, malicious operators have collected hundreds of millions of yen. The FSA says it will step up oversight against such companies, and will continue to submit warnings when it finds wrongdoing.