The government will tighten surveillance of sex offenders in response to a series of high-profile sex crimes. The measure targets those convicted of offences against children and teenagers.

The National Police Agency says it will add more personnel to its sex offenders' taskforce from next Wednesday, claiming the special team will work in rotation around the clock and all year round. The agency says it is on the lookout for 130 extra officers to join the already 200-strong taskforce.

There are currently over 5,300 registered sex offenders in the country. They are required to keep the police updated on their address, profession and license plate number, but over 50 are unaccounted for.