It was one of 12 sacks containing a total of 40,805,000 yuan (£4.2 million) being driven through the Hong Kong airport, Chinese website Shanghaiist reported.
CCTV footage showed three of the bags falling off the trailer as it turned a sharp corner on Friday, with the driver not realising they were missing until he arrived at a depot 10 minutes later.
He managed to retrieve two sacks, labelled G4S International, from the tarmac but the third was not recovered, prompting police to launch a theft investigation.
A spokesperson for G4S told The Independent the money was out of the firm’s control when it went missing in the care of Hong Kong Airport Services, a subsidiary of Cathay Pacific.
