A clerk working for the Hong Kong branch of a multinational company gave HK$200 million of the firm's money to fraudsters after being tricked into joining a video conference where all the other participants were AI-generated deepfakes, police said on Sunday.

The clerk was the only real person on the video chat and while the rest of them looked and sounded like the worker's colleagues, they were in fact characters created by the scammers based on genuine online conferences held in the past.

"[The fraudster] invited the informant [clerk] to a video conference that would have many participants. Because the people in the video conference looked like the real people, the informant... made 15 transactions as instructed to five local bank accounts, which came to a total of HK$200 million," said acting senior superintendent Baron Chan.

"I believe the fraudster downloaded videos in advance and then used artificial intelligence to add fake voices to use in the video conference."

Chan, from the force's cyber security division, said the incident last month started with the clerk receiving a message purportedly from the company's chief financial officer inviting them to a video call to discuss confidential transactions that had to be made.

The clerk only realised it was all an elaborate scam after later speaking to the company's head office, Chan said.

"We want to alert the public to these new deception tactics. In the past, we would assume these scams would only involve two people in one-on-one situations, but we can see from this case that fraudsters are able to use AI technology in online meetings, so people must be vigilant even in meetings with lots of participants," he said.

Police said that to avoid falling victim to fake online meetings, people should confirm the details through regular communication channels, and ask questions during video conferences to check the other participants are real and who they say they are.