MINI-motorcycles causing a menace on roads are being seized by police worried that the new craze could end in tragedy.
The small-scale machines are incredibly powerful and people believe they are toys.
But riders need to be fully insured, have a motorcycle licence and wear crash helmets by law to use them on roads.
Not only that, the bikes - some under 50 centimetres (20in) high - need to have fully working lights, indicators and number plates.
But there is no room on the tiny machines for them.
Sgt Andy Addy, of Huddersfield traffic police, said officers had confiscated about a dozen of the mini-bikes in Kirklees over the last two months.
He added: "These bikes must not be ridden on roads, pavements, playgrounds or any other public areas under any circumstances.
"It is illegal and people cannot get insurance for them as they can never be made road legal. So riders are in a Catch 22 situation.
"They can only be ridden on private land - but even then the engines can be very loud and cause noise pollution.
"If this is the case, Kirklees Council officials may look at taking action against them."
Once the bikes are confiscated by the police people have to provide proof of insurance to get them back.
Alternatively, they can pay the cost of recovering the bike from a police garage and storage charges - and then face prosecution and a fine for having no insurance.
If this is the case they will then get a minimum six penalty points on their driving licences.
If the bike is not claimed within 14 days it gets even smaller. It is crushed.
Sgt Addy said there had been complaints about the little bikes from drivers of large vehicles, such as Kirklees Council dustbin and street cleaning lorries.
The bikes are virtually impossible to see by other road users and police fear a tragedy.
Sgt Addy said: "These machines are miniature motorbikes that can rattle along at a fair speed."
If bikes are seized from people under 16 their parents face prosecution for allowing them to be ridden illegally.
The bikes are scale models of powerful racing machines and sell for about £500.
The makers make them for off-road use, ideally properly-organised race events.
But parents are buying them as toys and ignoring the obvious risks and dangers.
The bikes are widely for sale on the internet.
One site proclaims: "Serious thrillseekers and hedonists should waste no time in climbing aboard one of these.
"This bike can achieve amazing speeds of approximately 37mph, which feels mind-blowing when you're a matter of inches from the ground."
Supercharger kits are even available to give the bikes more power.