The parents of Amanda Dowler have been sending text messages to her mobile phone since she disappeared, it has been revealed.

Bob Dowler, 50 and Sally, 42, said on Tuesday - Amanda's 14th birthday - they were continuing to hope they will receive a reply, despite the fact the phone has not been found.

Amanda - also known as Milly - would have been celebrating her birthday with a pool party or barbecue and her parents were planning to buy her a digital camera.

The teenager vanished in March while walking home from the train station in Walton-on-Thames, Surrey.

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Police have warned the couple there is little chance of finding her alive.

The couple said in a statement: "We usually celebrate Milly's birthday with something like a pool party - we have a 12-feet splash pool that we put up in the garden and have a barbecue, with a dozen or so of her friends.

"She usually does something like that for her birthday. Maybe this year she'd have wanted a karaoke party.

"Milly really loves her karaoke - we'd probably have bought her karaoke tapes for her birthday. She loves all the usual teenage stuff."

Mrs Dowler said she has sent Milly text messages on her mobile phone, which has never been found.

'We're struggling'

"I find it really hard every time I buy something for Gemma - it's a horrible feeling, because I should also be getting something for Milly."

The couple said they never imagined Milly, who has a 16-year-old sister Gemma, could disappear without trace for so long, but they were "touched" by people's reactions.

Milly on her fourth birthday

"We're struggling to fill the days. We try to set ourselves a project but it's hard to remain motivated - we end up just going through the motions.

"But we have to try to hold it together for Gemma. She gets very upset when she sees us upset, and wants us to keep positive and brave.

"There are so many things we miss - especially her playing her saxophone. The lack of noise is very noticeable - the house is so very, very quiet now."

Superintendent Alan Sharp, of Surrey Police, said: "Our thoughts are with Amanda's family, particularly at this very difficult time.

�100,000 reward

"We offer them every sympathy and continue to put all our efforts into finding Amanda."

The Dowlers have also given permission for Surrey police to release a new home video of Amanda in an attempt to yield more clues about her disappearance.

Police have found no trace of Milly despite a massive search, more than 300,000 calls from members of the public and a �100,000 reward line.

A 52-year-old man from Ashford, Middlesex, was arrested in June in connection with Milly's disappearance.