Illegal and heading here: 'Killer' 20mph petrol-driven rollerblades

But these motorised rollerblades could cause serious injury and death, safety experts warned last night.

The Chinese-made boots are illegal across the world, but trading standards chiefs fear the UK black market is about to be flooded with them.

With a 25cc engine attached to the right boot along with a small fuel tank, they carry the wearer along at up to 20mph.

They are controlled using a handheld throttle and can reach maximum speed within seconds. But there is no brake. The only way of stopping is a shut-off button which acts like an emergency stop, throwing the skater forward at speed.

If they were legal they would be classed as a motorised vehicle and the user would need a driving licence, insurance and L-plates.

Fifty pairs of the boots, called Gasoline Skating Shoes, have been seized at an address in Bournemouth. It is believed they were to be sold on the streets and internet for up to £150 a pair.

David Morton, of Bournemouth trading standards, said as well as the speed danger, the skates have a plastic petrol tank which poses a serious fire risk.

'These things are absolutely frightening and would have been every parents' nightmare had they been on the streets. The skates are so dangerous that we are worried about putting them on to test them.'

The engine, weighing about 10lb, is carried in a 7in box on the heel of the right boot. The fuel tank is under the engine and holds a litre of twostroke fuel. The left boot is unpowered and just follows the impetus created by the right one.

'There is an exhaust vent and a cable to start the engine, just like a petrol-driven lawnmower,' said Mr Morton. 'The engine is 25cc and when you think that a moped has a 50cc engine then it is quite frightening how fast they can go.

'The hand-held throttle lever is attached to a one-metre lead and there is a button which kills the engine.'

He added: 'With a plastic petrol tank there are fears that in the event of an accident the whole thing could go up in flames, along with the user.'

Customs officers discovered the consignment at Southampton Airport. They tipped off trading standards officials in Bournemouth who went to the address of a man in his 30s.

They found two pairs at the house and 48 more in different sizes and colours at a nearby lock-up. It is thought the skates had been flown in from China via Amsterdam.

Mr Morton said: 'As far as we can make out the man was about to sell them for about £150. He was going to leaflet the area and probably use eBay as well and his target market was young people.'

An investigation has been launched with a view to prosecuting the man using legislation under the Consumer Protection Act.

Criminal gangs are flooding Britain with fake Heely shoes and using the proceeds to fund drugs and arms trafficking, it is claimed.

Customs and trading standards officials have seized thousands of imitation pairs from ports and warehouses.

However, an estimated 20,000 pairs, worth more than £1million, have slipped through the net. The shoes, basically trainers with wheels built into the heels, have been tremendously popular over the past two years.

Experts reckon the black market trade is funding more sinister crimes such as drug trafficking, people smuggling and even terrorism.

Trading Standards Institute spokesman Bryan Lewin said: 'There is more to worry about than simply a very badly-made and potentially unsafe product when people buy counterfeit Heelys.

'The money from the sale of fake Heelys and other counterfeit items funds a whole range of illegal activities which include drugs, weapons, terrorism, money-laundering and organised crime.'