Parents could buy phones without internet access for their kids to protect them from harmful online content, the Children's Commissioner has said.
Dame Rachel de Souza expressed alarm at some of the material young people are seeing on the internet, and said parents "should think long and hard about monitored access to social media or actually access to social media at all".
The children's tsar pointed to the tragic case of 14-year-old Molly Russell, who viewed graphic posts about suicide and self harm before taking her own life.
Dame Rachel, who was asked to lead a review into online safety for children by the Government, found it is “quite likely” for eight-year-olds to come across pornography online and for teenagers to find “insidious” violent content.
She told The Telegraph: "I feel strongly that we need to be careful and manage this.
"So, if you're worried about your child walking home from school, for example, buy a non-internet-connected phone, so they can always contact you."
Dame Rachel added: "Now, we know the internet can be an amazing resource. But I think we also know the problems and the darker side - whether it's access to pornography, violence, gore, dieting material.
"And what the Molly Russell story really shows us and, talking to her Mum and Dad, is just that they didn't know what she was looking at."
Schools are "getting better at advising around the phone issue because it's just such a massive issue", she said.
But she added: "I honestly think that we will look back in 20 years' time and be absolutely horrified by what we allowed our children to be exposed to."
Dame Rachel described children's experience online as "the issue of our age", and said the long-awaited Online Safety Bill must be brought to Parliament as quickly as possible.
"We absolutely need to take this once-in-a-generation moment to ensure children are kept safe online and in the online world. Nothing should get in the way of supporting child safety online and getting this Bill back," she said.
The bill was carried over from the last parliamentary session but there are fears it could be delayed again.
Culture Secretary Michelle Donelan has said she wants to make tweaks to the proposed legislation but is committed to bringing it back to the Commons.
