The number of e-scooters on the roads in west London is set to soar as the capital, including Hounslow Council, prepares to launch a trial of the vehicles in the coming weeks.

They have been hailed as a greener, more sustainable mode of transport that can reduce traffic congestion, but concerns have been raised after trials in other UK cities.

Newcastle has introduced an overnight curfew for e-scooter riders after a spate of drink-driving arrests.

A councillor in Merseyside recently branded the devices "orange death traps" after witnessing people riding them on pavements.

In Leicester a six-year-old boy suffered a fractured skull after being struck by a teenager riding one of the vehicles.

So what are the worries about the surge in e-scooters?

The sister of a six-year-old boy who suffered a fractured skull after being struck by an e-scooter said she has concerns about their increase on UK roads.

Jamie Smith was sent "somersaulting" through the air and was knocked unconscious outside his home in Leicester after being hit by a teenager riding one of the devices.

Jamie's sister Brooklyn Smith, 21, said she feared for her brother's life as he was airlifted to hospital after the incident in August.

Ms Smith told Sky News said she believed e-scooters needed to be made safer to avoid other people getting hurt.

"I don't think we can get to the point where we can ban them all together," she said.

"I think they definitely need to make them a lot safer and help make sure this doesn't happen to another child again.

"They need to have some form of testing where if you've got points on your licence or anything like that, because you've been driving without a licence or driving irresponsibly, you shouldn't be able to go on (an e-scooter)."

London is preparing to launch a trial of e-scooters in the coming weeks, with the devices expected to be deployed in 11 out of 33 boroughs in the capital in May.

Riders need to have a full or provisional car, motorcycle or moped licence, and have been urged to wear a helmet.

Only rental e-scooters are allowed on roads, and they are limited to 15.5mph.

Privately-owned e-scooters cannot be used on the UK's roads due to their classification as a motor vehicle under the Road Traffic Act 1988.

Motor vehicles are required to have number plates, with users needing to have a driver's licence, insurance and wear a helmet.

In October, MPs recommended that e-scooters should be legalised in the UK within 18 months to help make cities greener.

A consultation by parliament's transport committee found the vehicles could be an effective way to cut car journeys and clean up the air.

But the MPs said e-scooters should remain banned from pavements for pedestrian safety.

Throughout the trial in Hounslow, the council says it will review ride data and resident feedback to make alterations to the scheme and add new 'no go' or 'go slow' areas where necessary.

The council said the use of privately-owned scooters on public roads or pavements will remain illegal during the trial, and the Metropolitan Police Service (MPS) will be undertaking enforcement activity to deal with them.

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