Nearly 700 sex offenders including 157 child abusers have been taken off the register in the last four years, according to reports.
The criminals, who had convictions including the rape of boys and girls, incest and taking indecent photos of children, were told they no longer had to register with the police, it is understood.
A freedom of information request showed more than half of applications made since 2012 were successful, the BBC said. They included 170 rapists - 27 of whom raped people aged under 16 - and three people who committed incest with children under 13.
It comes after a ruling by the Supreme Court in 2010 allowed sex offenders to appeal against being held on the register for life.