The whereabouts of nine convicted child-sex offenders who have been released from prison since the National Police Agency started keeping track of them in June is unknown, the agency said Thursday.

The Justice Ministry has given the NPA information on 96 people convicted of molesting children under the age of 13, and 83 of them had been released as of the end of November. But nine of those 83 can't be located, the agency said.

Of the nine, eight did not report their addresses prior to their release and vanished immediately after they were released, it said.