The Met has said it will continue to respond to the large scale illegal use in order to keep road users and the public safe.
At least three riders were killed and 291 Londoners hurt in crashes in the past year, according to Department for Transport figures which are likely to be an underestimate.
Watch: Dozens of people left injured after being hit by e-scooters in UK last year, figures reveal
Riders face fines, points on their licence and adding to the 3,637 e-scooters seized if they continue to use them on the public highway.
Scotland Yard and Transport for London have written to businesses selling them in London reminding them of existing legislation and how they may be putting their customers at risk of enforcement action.
Commander Kyle Gordon, in charge of Roads Policing, said: “It is really unhelpful that retailers, fully aware of the risks they are creating for the public, continue to profit from selling machines illegal for use on public roads without sufficient explanation and guidance.
“This is leaving many with expensive seizures, fines and points on their licence.
“I am calling on retailers not to exploit their customers in the run-up to Christmas simply to make a profit.
“Private devices have, on occasion, proven to be highly dangerous; and we have been called to help many people who have been involved in collisions and ended up seriously hurting themselves or others.”
Only e-scooters rented through an approved trial scheme are legal to use on the road.
London is one of 40 towns and cities taking part.
In the city, the 3,585 rentals must not exceed 12.5mph, 55kg and include always-on lights.
Users must be over 18 and hold at least a provisional licence.
Will Norman, the mayor’s walking and cycling commissioner, added: “E-scooters have been on our streets for a while now with a woeful lack of regulation, and we know they’re not going away.
“That’s why we are running a rental e-scooter trial in London with much safer, legal rental e-scooters, to take learning from and to see what part e-scooters can play in London transport as we recover from the coronavirus pandemic.
“However, private e-scooters can be extremely dangerous, and anyone deliberately misusing them will feel the full force of enforcement action.”
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