Hong Kong's securities regulator said on Monday it had begun investigating a virtual currency exchange platform that police say has defrauded people of nearly HK$150 million, shortly after receiving complaints.

Julia Leung, chief executive of the Securities and Futures Commission (SFC), said the body had so far received 18 complaints about Hounax, each involving between HK$12,000 and HK$10 million.

She said the regulator became aware of the platform through complaints, before it flagged it as suspicious and put it on a watch list earlier this month.

"We received our first complaint at the end of September... We started investigating at an early stage - in October," Leung told reporters.

"We do not just rely on complaints. Complaints are one of the clearer warnings of possible fraud. In fact, we are constantly checking social media for platforms that have not applied for a licence."

Leung also said there's no need to adjust the grace period for companies to apply for a virtual asset trading platform licence after the new rules came into effect in June.

"Even if the grace period is over, or if I say it ends tomorrow, scams will still continue to happen," Leung said. "We should give enough time [for the application], and we have said in advance that the period will be one year. We should stick to the original requirements."

Leung said the commission had "zero tolerance" for any violations and would not sit idly by, adding that it would not shirk its responsibilities and would take prompt action to protect investors.