Social media and online gaming firms should have a statutory “duty of care” to protect children from mental ill health, abuse and addictive behaviour, a coalition of the country’s leading experts demands today.

Data amassed by charities, academics and doctors links children’s use of social media and gaming to a range of serious and lasting harms, many of which build gradually over time and go undetected by parents or teachers.

They accuse businesses such as Facebook and Snapchat of cynically targeting children as young as eight, using addictive “hooks” from the worlds of behavioural psychology and gambling to capture “new skins” to keep them logged on for as long as possible.

Experts say existing controls are not effective, with charities like Barnardo’s reporting a growing number of middle-class children seeking help with issues such as internet addiction, sex texting, grooming and online bullying.

The Daily Telegraph today launches a duty of care campaign, as ministers consider new measures to rein in the worst excesses of online firms which it is feared are now harming a generation of young people.