One of Britain's biggest mobile network operators said on Sunday it will warn parents they should not give smartphones to children under the age of 11.

The new guidance comes after growing concern from parents about the potential pitfalls of smartphone access for young people.

A recent study by the UK communications regulator found around a quarter of British children aged between five and seven-years-old now had a smartphone.

EE will say in new guidance that children should only be given phones with "limited capability devices" allowing them only to text and call.

It will also advise enabling parental control features for teens under the age of 16 and restrictions on social media for the under-13s.

UK parents have increasingly started to push back against the trend of giving children one of the devices when they transfer from primary to secondary school at the age of 11.

Widely justified on safety grounds in case of an emergency on the way to or from school, parents fear the phones also potentially open children up to online predators, bullying, social pressure and harmful content.

"While technology and connectivity have the power to transform lives, we recognise the growing complexity of smartphones can be challenging for parents and caregivers," said Mat Sears, EE corporate affairs director.

"They need support, which is why we are launching new guidelines on smartphone usage for under 11s, 11 to 13-year-olds, and 13 to 16-year-olds to help them make the best choices for their children through these formative years."

US author Jonathan Haidt -- whose recent book "The Anxious Generation" argued that smartphones have rewired children's brains -- has urged parents to act together on smartphone access so it becomes the norm for children not to have one.

A child "breaks our heart" by telling us they are excluded from their peer group by being the only one without a phone, he said earlier this year.

Haidt advocates for no smart phones before the age of 14 or social media before 16.

"These things are hard to do as one parent. But if we all do it together -- if even half of us do it together -- then it becomes much easier for our kids," he added.