The deputy chief executive of the Child Exploitation and Online Protection (Ceop) centre has warned the internet "amplifies" the opportunities of paedophiles for abuse.
Andy Baker told ITV News, "They send out hundreds if not thousands of emails to children they spotted on social networking sites - they've seen their profile, they research them, and they also contact them as if they know them."
Mr Baker said the paedophiles then "dupe" the children into believing that they are around the same age and "pretty quickly" ask to see explicit pictures of them.
"Once you pass over that photograph that's it - that's the start of this real sexual extortion and demand, and then the fear kicks in," he added.
Hundreds of British children - some as young as eight - are being blackmailed into performing sex acts online by paedophiles.
Hundreds of British children are being blackmailed into performing sex acts online by paedophiles, an investigation has found.