Hong Kong police are investigating an attack and robbery in which a man lost about HK$6 million (US$767,070) in cryptocurrency and silver.

The force said it received a report at 3.52am on Saturday that a 25-year-old mainland Chinese man was attacked by three men and a woman at a hotel near Man Lok Street in Hung Hom and robbed of cryptocurrency worth HK$5 million from his account.

The suspects later took the victim to another unit in an industrial building, where they seized silver items worth HK$1 million.

No arrests had been made so far and a manhunt was under way to track down the four suspects.