By ANDY DOLAN

Last updated at 16:39 05 March 2008

Meet the pistol that fits in your pocket - and packs a hell of a punch.

The SwissMiniGun is the size of a key fob but fires tiny 270mph bullets powerful enough to kill at close range.

Officially the world's smallest working revolver, the gun is being marketed as a collector's item and measures just 2.16 inches long (5.5cm). It can fire real 4.53 bullets up to a range of 367ft (112m).

The stainless steel gun costs £3,000 although the manufacturers also produce extravagant, made-to-order versions made out of 18-carat gold with customised diamond studs which sell for up to £30,000.

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At just over two inches long it is the world's smallest gun - but the 300mph bullets it fires mean it is still deadly

It cannot be imported into the UK, and buyers in Switzerland and Europe must produce an import permit from police to obtain one.

The gun is banned from being imported into the US - because it's barrel is less than three inches, meaning it is deemed too small to qualify for sporting purposes.

Jonathan Spencer, consultant forensic scientist and firearms expert, said that although the gun, which fires bullets at a speed of 399 feet a second, was tiny, it could still prove fatal and in the eyes of the law was as dangerous as a machine gun.

He said: "The general threshold for perforating the skin is about 330 feet a second.

"Apart from bone, skin offers the greatest resistance to penetration. If it can pass through the skin it is potentially lethal, even if the bullets are small.

"If you shoved something 3mm across into someone's chest you could kill them. It's the same with these bullets, they could penetrate the heart.

"It is capable of killing someone. Under section 5 of the Firearms Act it would be a prohibited weapon. It would be on the same scale as a machine gun."

The gun shoots 2.34 mm calibre rim fire ammunition especially developed for it as the smallest rim fire ammunition in the world.

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The Swiss Minigun, which is being marketed as a collector's item, is just 5.5cm long, and fires 4.53mm bullets up to 112 metres

It weighs in at just 0.7oz (19.8grams) and fires live and blank ammunition.

The gun is the first product of the SwissMiniGun company, a gunsmiths based at La Chaux-de-Fonds, Switzerland.

Owner Paul Erard said that since the product's launch three years ago, the firm had sold around 300 of the guns, mainly to collectors in the Middle and Far East.

He said: "We are producing in very small quantities - perhaps 25 gold guns and 100 steel guns a year, and there is a six month waiting list to get one.

"We will make whatever the customer wishes for. The most expensive version we have sold cost £30,000 and was covered in diamonds and came with a gold chain."

Other bespoke finishes available include ebony grips, hand engraved grips, gold grips with diamonds or collared precious stones.

Mr Erard said that although the double action revolver is similar in appearance to a Colt Python full-size weapon, it was actually based on a Swiss-made revolver.

In September 2006 the Bureau of Alcohol, Tobacco, Firearms and Explosives(ATF) in New York issued a warning about the gun after being alerted by a police officer who spotted it on a website.

Special Agent William McMahon said the gun was so small it could pass for a key fob, and warned it made the perfect stealth weapon for serious criminals.

But Mr Erard denied the gun was deadly and said it was only a tenth as powerful as some air guns.

"Since September 11 there has been a lot of paranoia in America", he said.

"It is ridiculous. Why would criminals want my gun when you can go out and buy a Kalashnikov there already?"

A Guinness World Records spokesman confirmed the gun held the record as the word's smallest working revolver.