The number of people on the Garda's register of sex offenders has grown to 915 since it was established almost five years ago, new figures show.
The Garda does not refer to the list of names as a "register", although the term has been used in the past by the Department of Justice and the courts.
The Garda's domestic violence and sexual assault unit says it maintains a "notification list", a register of names and addresses of sex offenders who are obliged to provide gardaí with details of their whereabouts.
However, a range of groups such as the Irish Society for the Prevention of Cruelty to Children and the Rape Crisis Network Ireland say the measures are not as robust as in Britain and point to a series of gaps in child-safety procedures.
The Sex Offenders Act sets out a range of obligations for individuals convicted of sexual offences.
A convicted sex offender must contact the Garda with details of their home address within seven days of their conviction or, where the offender is sentenced to imprisonment, from the date of their release from prison.
After this date, the offender must notify the Garda of any change of name or address or details of any location where they plan to spend more than seven days.
If the offender intends to leave the State for a week or more, they must provide the Garda with details of their address.
These provisions extend to any sex offenders entering the jurisdiction who have an obligation to register in their own countries.
It is an offence to fail to comply with notification requirements. The penalties are imprisonment for up to 12 months or a fine of €1,900 or both.
It is not clear, however, what resources are devoted to pursuing those who attempt to evade the conditions of their registration.
The courts can also sentence an offender to a period of "statutory supervision" under the Probation and Welfare Service on their release from prison.
The Rape Crisis Network has called for an assessment of sexual offenders before their release from prison which would identify the level of supervision and regulation needed for an individual.
The Department of Justice has said that provisions relating to monitoring and notification procedures relating to the Sex Offenders Act, 2001, are kept under review.
The ISPCC has called for a properly resourced monitoring and registration system.
"The figures clearly indicate that there are significant numbers of people who represent a real and ongoing risk to children and that society is obliged to ensure that all possible safeguards are introduced to protect children," the ISPCC said.