Claudia Lawrence, 35, who was born and bred in the town, was last seen as she walked home from work in York 13 days ago.

The appeal comes as Det Supt Ray Galloway, who is leading the investigation, appeared on BBC One's Crimewatch last night.

Speaking at Miss Lawrence's favourite pub, The Spotted Cow in Malton, Liz Holder said she is "constantly worried" for the friend she has known for 12 years.

"It's just an awful feeling not knowing," said the 28-year-old who last heard from Miss Lawrence the night before she vanished.

"Every time the phone rings, you don't know what's coming. I have made myself feel quite ill really because I have not been sleeping."

Ryedale MP John Greenway, a friend of Miss Lawrence's father, Peter Lawrence, added: "Somebody somewhere must know where Claudia is and what has happened and we just have to use every opportunity to try and jog someone's memory.

"She was a Malton girl and everybody is concerned and understandably so."

And Malton mayor Jane Ford, who sits on the town council with Miss Lawrence's mother, Joan, added: "I just hope and pray that Claudia hasn't come to any harm and will get in touch with her mum."

Miss Lawrence, of Heworth Road, York, works as a chef at the University of York's Goodricke College. She spoke to her parents a week last Wednesday and was due to meet a friend for a drink at the nearby Nag's Head pub but failed to turn up.

North Yorkshire Police believe she disappeared at around 5.30am the next morning after she left home with no money, cards, or passport to walk the three miles to work.

A wide police search, involving civilian search and rescue teams, and a poster campaign by family and friends has so far failed to locate her.

Dr John Sentamu, the Archbishop of York, led prayers for Miss Lawrence along with clergy at other churches in Malton, Norton and Old Malton and in Heworth, York, over the weekend.

Mr Lawrence said: "We hope also that you will remember others who have loved ones missing at this time. For our part, we are trying to keep strong in our faith through this difficult period, in the belief that hope will prevail and that, once again, we will be physically reunited with Claudia, and express our continued, everlasting love for her."

Mr Lawrence also made a televised plea on BBC One's Missing Lives on Friday.

l Meanwhile, North Yorkshire Police yesterday issued a warning about a website which is operating without any involvement from themselves or Miss Lawrence's family.

They urged the public not to visit or donate any money to the "Claudia Lawrence Appeal" on www.claudialawrence.com