Since the first of March, this type of cheating has been illegal. The Swedish Transport Administration reports the person caught to the police on suspicion of "false declaration", a crime that can result in a fine or up to six months in prison.

But Mazen Dayoub's boss, Anki Juhl, wants even tougher sanctions against the cheaters and better equipment on the premises to detect them.

In the clip above, Mazen explains how cheating usually happens - and how he discovers it.