Sean Ryan went missing in 1998

Searches for a missing person can be conducted on the site using details of physical descriptions such as height, weight and hair colour.

Photographs and details of adults who were with the children when they disappeared can also be published.

Posters of the missing person can be printed directly from the site and displayed in areas where there are reported sitings.

Global information

The supermarket chain Tesco in Ireland has already agreed to print and display posters routinely or when specifically requested.

RUC Inspector Bob Torrens said cases of missing children created terrible suffering for families.

"Children are so vulnerable and can so easily become victims of crime," he said.

"Even teenagers, who probably think they're worldly, can quite easily become victims of sinister older people."

The site is hosted by Computer Associates International Inc and was piloted in the UK by the Metropolitan and Hertfordshire Police.

It also provides a link to global information about missing and exploited children.