Police have found no evidence of a struggle

Police are also using information from CCTV footage, aerial photographs and items taken from the family home to build up a profile of Amanda.

Her computer has been checked to see if the schoolgirl was using internet chat rooms or might have met a man via the web.

And detectives have widened their search for the teenager to include the whole of the Walton-on-Thames area.

A police spokesperson said: "We are keeping a very open mind as to the reasons behind Amanda's disappearance."

Despite more than 1,000 calls to the incident room in Surrey, police have found no trace of Amanda.

Detectives say there was no evidence of a struggle.

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They believe it was more likely Amanda went off with someone she knew, rather than being abducted by a stranger.

Twenty extra officers were put on the case at the weekend to cope with the public response generated by recent appeals for information.

As well as her phone Milly was carrying a beige rucksack, a white plastic purse with a heart in the top right hand corner, and a pencil case when she disappeared.

Police have also searched the teenager's home with the consent of her parents Sally and Bob.

Their other daughter, 16-year-old sister Gemma, has made an appeal to anyone who may have abducted her sister.

"If someone has taken Milly, please return her safely to us as I am missing her very much and I couldn't wish for a lovelier sister," she wrote.