Hong Kong  - A YouTube clip viewed by 48,000 people has exposed a scam in which Hong Kong optical salesmen steal people's spectacles and then try to sell them new ones, a consumer watchdog said Thursday.

According to Hong Kong's Consumer Council, the video showed a staff member from an optical shop stealing a woman's spectacles while she was on the phone in the street.

He is later seen leading the woman into the shop to buy new ones.

The scam aired on the internet in March alerted the council to look in to the scam, leading to the discovery of four other similar complaints this year and eight in 2008.

The council on Thursday issued a warning to the millions of Hong Kong people who wear glasses to be on their guard over the trick.

At least half of Hong Kong's 7 million people wear spectacles.

The council said the shop in the video clip has since closed. (dpa)