Stricter rules regarding the use of booster seats will come into force later this year, limiting the use of backless booster seats to older children.
At the moment, children weighing as little as 15kg, around three years old, can travel in backless booster seats.
But under the new rules that will come into effect in December, backless booster seats will only be approved for use by children taller than 125cm and weighing more than 22kg.
The current UK law states all children travelling in a car must use the correct car seat until they are 12 years old or 135cm tall, with many parents buying their young children a backless booster.
But child car seat experts from consumer organisation Which? say that this type of booster seat is unsuitable for such young children.
They say a small child is not held as securely in the seat, the adult seat belt is not guided across their body in the best way, and, most importantly, a booster seat offers no protection for a child if your car’s involved in a side-impact crash.
A backless booster seat, also known as a booster cushion, currently satisfies the legal car seats law requirement for children up to 135cm tall, and are cheaper, but are not recommended.
Which? child car seat expert, Lisa Galliers, said: "A decent high-backed booster seat provides better protection in a front crash, as they’re designed to guide the adult seat-belt across the child’s body properly.
"Our crash tests prove they offer much more protection in a side-impact crash than a backless booster seat alone."
The new rules will only apply to any new products appearing on the market, meaning parents buying a booster seat next year should start to see that they are not approved for use with children under 125cm and 22kg.