THE number of minimoto bikes has risen by more than 10 times in recent years.
But many are still being ridden illegally, putting the lives of their riders and other people at risk.
Road safety officers countrywide say the craze is continuing - despite repeated warnings that it is illegal to ride them on road and pavements and in parks.
If riders are caught the police seize the bikes, which are then destroyed.
It is unclear exactly how many mini- motos there are in the UK, but the Motorcycle Industry Association reckoned there were 10,000 in 2002 and 100,000 by 2005.
The small machines are very powerful and people believe they are toys. But riders must be insured, have motorcycle licences and wear crash helmets to use them on roads.
Not only that, the bikes - some under 20in high - need to have fully working lights, indicators and number plates.
But there is no room on the tiny machines for them, so they are illegal, unless ridden on private land or racetracks.
Simon Ettinghausen, chairman of the Local Authority Road Safety Officers Association, said: "Despite enforcement action and awareness-raising of the anti-social problems, misuse of these vehicles is increasing at an alarming rate.
"It is dangerous, as many youngsters ride them without helmets or the proper safety equipment.
"They also cause misery to communities where there is a constant fear of being mown down by one or having to listen to the noise."
A pioneering scheme has been set up in Durham where there is a big problem with the machines.
The county council and the police are launching a minimoto club.
A police spokesman said: "If we can provide them with a safe environment to ride it may help reduce the problem of them riding illegally.
"We also get the chance to make sure youngsters get the road safety message."