An "alarming spate" of fires have been caused by unsafe e-bike and e-scooter batteries and chargers.
According to Freedom of Information data, obtained by the insurer Zurich, the number of fires caused by batteries has surged almost 150% in the last year.
Firefighters in London were called to 88 fires by e-bikes last year, an increase on 80% on 2021.
Assistant commissioner for fire safety Charlie Pugsley said the devices are often stored in communal areas and corridors, blocking people's only means of escape, which means a situation can quickly become incredibly serious.
"When these batteries and chargers fail, they do so with ferocity," he said.
As a result, consumers are being warned to only buy e-bikes and -e-scooters from reputable retailers. These vehicles will display a valid UKCA or CE mark.
Christine Heemskerk, lead officer for product safety at the Chartered Trading Standards Institute, said that individuals need to be "really certain" where a product is coming from and the right charger with the right battery is being used.
The fires have been attributed to non-complaint lithium-ion batteries, which are being imported by businesses and fail to meet UK product safety laws.
Alonso Ercilla, trading standards manager at the London Borough of Islington warned of the dangers on businesses if they keep getting this wrong.
"We advise anyone selling these devices to get them tested to make sure they comply with product safety laws. When things go wrong, there are consequences. Businesses can be prosecuted and the public can be exposed to great risk of harm," they said.
Privately owned e-scooters remain illegal in public places in London, but are not illegal to purchase.
Lesley Rudd, chief executive of Electrical Safety First, called on the government to regulate online marketplaces in order to "better protect the public".
In June last year, data provided by the Department for Transport showed incidents involving e-scooters was three times higher than the previous year.
There were 1,349 recorded collisions and 1,437 casualties in the year to the end of June 2022, an increase from 978 crashes and 1,033 casualties recorded the year before.
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