London: Health campaigners have warned of a “ticking time-bomb” after it was claimed that a million children have been given mobile phones at around the age of five.

Parents appear to be using the handsets as babysitting devices to keep children entertained at home or on long journeys.

Many families apparently also see them as an important safeguard to check where children are playing.

The Department of Health says children should be discouraged from using mobiles, particularly if they are held next to the head, while the country’s chief medical officers say children and young people under 16 should be encouraged to use mobiles for essential purposes only, and to keep calls short.

Campaigners insist there is strong evidence to link brain tumours to mobile phone radiation and that to allow children to use them is exposing them to risk. Graham Lamburn, of the Powerwatch health campaign group, said: “The very idea of letting children have mobile phones at the age of five is very irresponsible.

“We have the greatest body of evidence to demonstrate that mobile phone radiation is a brain tumour risk for adults. If that is the case, children are almost definitely at a greater risk. Giving mobile phones to children represents an enormous experiment in terms of their health.

“We won’t see anything in children for ten years, but this could very easily be a ticking time-bomb.”

Swedish research has suggested heavy mobile phone use over decades increases brain tumour risk by 2.5 times in adults and up to five times in children. However, there is a caveat that the number of people who fit into this category is very small. Price comparison website said children are given their first phone at an average age of 11 years eight months, coinciding with the move to secondary school.

But one in ten children, equating to about a million, is about five when they get a handset.

Ernest Doku, of, said: “If you do give in to your kids’ requests, asking networks to place caps on their mobile bills is a very sensible precaution.”