The trio are being detained as police investigate allegations that they attempted to extort money from Vietnamese shopkeepers in the Welse-Galerie II shopping mall.

Victims say that the three men visited their shops and asked for cash, which they referred to as “tax” or “protection money.” They threatened to destroy their businesses or use violence against them if they refused to pay, according to a police spokesman.

One trader reportedly informed the local police about the scheme and the trio were arrested shortly thereafter.

A 41-year-old man named Hoi is believed to be the gang’s ringleader. Police say Hoi has served time for attempted murder.

The police have also established a hotline (4664-94 31 10) so that annonymous tips can be left in Vietnamese on an answering machine.