POLICE and the Postmaster-General's office are joining forces to stop mail order advertisements that offer imported stun guns and tear-gas sprays. Advertisements in some local publications have billed the equipment as anti-rape devices and recommend it to women for their personal protection. But Chief Staff Inspector (Licensing) Rick Kent said yesterday anybody who bought and sold the guns and sprays would be breaking the law if they did not have a special licence. Mr Kent said police recently warned one Tsim Sha Tsui dealer advertising in the Chinese press that he was in breach of the firearms licensing law. ''Hongkong has some of the strictest firearms legislation anywhere in the world and these personal protection devices are not classified as firearms in many other countries as they are here,'' Inspector Kent said. ''They are in the firearms category because they project irritants. If they were available freely here, they may be put to different uses than originally intended.'' He said the force's licensing section have been working with the Postmaster-General's office to monitor mail order advertisements. ''We have also had some cases of people bringing these devices into Hongkong from other countries where they don't require licences,'' Inspector Kent said. ''When we tell people that they need licences for this equipment, every person so far has surrendered them to us because the firearms licence is expensive and we are very stringent in who we grant licences to. ''The licence costs $800 a year and we have not granted any licences for personal protection purposes.'' Anybody convicted of possessing firearms without a licence can face up to 10 years' jail and a maximum fine of $250,000.