A TERRIFYING weapon small enough to hide in a wallet but powerful enough to kill someone has been developed in Switzerland.



The SwissMiniGun is 5.5cm long and can fire 2.34 calibre bullets at 434km/h, and is scarily described as 'fun-sized' on the company's website.

Customs and Border Protection say despite the gun's size, they will be working with domestic and international authorities to try and stop it being imported illegally into Australia.