Chatrooms checked in Milly search

Amanda has used internet chatrooms regularly

Pop-up messages about missing schoolgirl Amanda Dowler will appear in internet chatrooms.

Detectives believe teenagers using the same chatrooms frequented by Amanda could provide a breakthrough in their investigation.

Surrey Police said the missing 13-year old, known as Milly, often chatted on-line from her home computer.

Among the websites that have agreed to carry the messages is one devoted to Pop Idol Will Young, Amanda's favourite pop star.

New users

Superintendent Alan Sharp said: "We want to hear from anyone who communicated with Milly in chatrooms or has any information that will help."

The message will pop up as soon as somebody new enters the chatroom and then every 20 minutes during their time online.

It will run daily from early afternoon until 2200 BST and contains the words: "Amanda (Milly) Dowler is a 13-year-old schoolgirl who has been missing from the Walton-on-Thames area in the UK since 21 March."

It then gives the phone numbers for Surrey Police and Crimestoppers.

A police spokeswoman said: "It is likely there are still things we don't know about Milly and we are encouraging people to come forward, anonymously if necessary."