Tsang Sik operates undercover - but he's no police officer. His latest secret mission was to expose how much edible food is being dumped by one of the major supermarket chains.
In six weeks working for ParknShop, every day he saw food being dumped before its expiry date - food that could have gone to the needy. His research helped Friends of the Earth conclude that 29 tonnes of edible food is dumped by supermarkets each day.
Tsang refuses to give his real name or have his photograph taken as he plans to conduct more undercover missions for the group.
Although staff had been reluctant to discuss the exact details of the food dumping, what Tsang saw led him to believe that there were hidden guidelines for supermarket workers to dispose of food before it had to be taken off the shelves.
'They don't actually dump food after the supermarket closes. It is an ongoing and organised task beginning right after the shop opens in the morning,' the young man recruited by the green group to carry out the investigation said.
'They also dump food even before it reaches its expiry date. I have seen a trash bag half loaded with about 50 packs of cooked food a few hours before their expiration.'