Among those convicted of sex crimes against children, 941 have reoffended since they were subject to registration requirements, according to figures obtained under freedom of information laws.
The figures, obtained by the children's charity NSPCC from the National Police Improvement Agency, showed that out of a total of 61,397 sex offenders, 29,837 were for crimes against children.
The charity called for the Government to provide an annual breakdown of the number of paedophiles placed under registration requirements, how many go on to reoffend, and how many cannot be traced in each geographical area.
Jon Brown, of the NSPCC, said: "Reoffending rates for sex offenders have risen in recent years, but until now we did not know how many of these involved the sexual abuse of children.
"From now on, we want a separate tab kept on the number of child sex offenders in this country and how many go on to abuse again.
"Sexual offending can be compulsive. Any offender with a history of child sex abuse should be considered a risk to children's safety for the rest of their lives.
"This is why it is so important they are closely tracked and monitored by the police once they are back in the community."
He said better information about paedophiles and reoffending rates would help protect children from abuse. "Monitoring these offenders is costly, time-consuming and very challenging. The more the authorities know about how convicted child sex offenders behave, the more effective they can be at protecting children from abuse," he said.
"Capturing information on convicted child sex offenders at both a national and local level can help the authorities detect any trends in convictions and reoffending rates for child sex abuse.
"It will also help local police forces learn from each other about which monitoring techniques and deterrents are the most effective at stopping child sex offenders abusing again. Being open about this information will also help reassure the public that everything possible is being done to protect children from known sex offenders."
The figures were released as it was reported that children as young as 10 have been arrested on suspicion of rape.
Figures obtained by a newspaper under a freedom of information request showed that 24 forces had detained children under 13 for suspected rape in the past year, and seven had arrested at least one 10-year-old.