Half of parents in Britain do not realise that their children could be committing a crime through "sexting", new research by the National Society for the Prevention of Cruelty to Children (NSPCC) concludes.
The charity said the number of children its ChildLine service had counselled specifically about the fall-out from sharing sexually explicit messages or photographs by mobile phone had jumped by 15 per cent last year alone.
But a survey of parents found that 50 per cent did not know it was illegal for children to share naked or sexual pictures of themselves.
Only around one in 20 parents believed their child was likely to send explicit images or videos of themselves to someone else.
Yet more than a third (35 per cent) said they would contact police if they found out their children had done so.
Peter Wanless, chief executive of the NSPCC, said: "Sharing nude selfies can put young people at risk of bullying by peers or being targeted by adult sex offenders, so it's vital that parents talk to their children and that young people feel empowered to say no to sexting requests.
"We realise that talking about sexting can be an embarrassing or awkward conversation for both parents and children.
"And although most parents said they would seek help if an indecent image of their child had been shared on the internet, half of them weren't confident about getting the right support.
"The NSPCC has created a new guide for parents to help them talk to their children about the risks of sexting, what the law says, and what to do if their child has shared a nude image that is being circulated online or among their peers."