The devastated parents of a missing architect broke down in tears today as they admitted they feared she had been abducted.

David and Theresa Yeates sobbed as they acknowledged that 25-year-old Joanna - missing since last Friday - could be being held against her will and begged for her to be returned safe and well.

Mr Yeates, 63, said: "I think she was abducted after getting home to her flat. I have no idea of the circumstances of the abduction because of what was left behind.

"I feel sure she would not have gone out by herself, leaving all these things behind, and she was taken away somewhere."

He added: "It's cold and I'm thinking that if she's out there by herself somewhere, frozen, it breaks me up. I long to hold her.

"I've got to believe she's alive. She had so much life in her. If it turns out she isn't alive, I still want her back and want to hold her whatever state she's in."

Miss Yeates has not been seen or heard from since Friday following a night out with work colleagues in Bristol.

Her boyfriend, Greg Reardon, 27, reported her missing on Sunday night after returning home to their flat in Canynge Road, Clifton, from a weekend away in Sheffield visiting family.

Detectives are investigating the possibility that Miss Yeates was abducted and said it was one of several lines of inquiry.

Miss Yeates was last seen leaving the Ram pub in Park Street at about 8pm, walking up the street.

She popped into a Waitrose on the way - where the last CCTV image of her was taken - rang her best friend to arrange to meet on Christmas Eve and then went to a Tesco Express a quarter of a mile from her flat at about 8.40pm.

A receipt from Tesco was found in her flat, along with the cream-coloured coat she had been wearing, and her mobile phone and keys.

Mrs Yeates, 58, said her daughter, known as Jo to her friends, had recently moved into a flat with her boyfriend and had been looking forward to a party they were holding for friends on Tuesday.

Sobbing and clutching her husband, Mrs Yeates said: "I miss being able to hold her and cuddle her and tell her everything's all right.

"I just want her back. My little Jo - come back. Whoever has got her, don't keep her. Give her back to us.

"Nobody can feel the pain we feel."

Mr Yeates said he believed his daughter was abducted because she had no reason to take her own life or suddenly disappear.

He said: "Her graduation was a couple of weeks ago. Her and Greg were totally in love and devoted to each other. She had all the space she wanted and no work worries and no money worries.

"If she chose to go away she would have taken some of her things with her, like her purse and her phone. I never thought for a second she would leave on her own volition.

"Greg has been away before and come back and every time she has been there. It's not the first time he has been away for the weekend.

"Jo didn't always answer her phone in a timely manner. We thought it was strange she didn't respond to our call at the weekend but it was consistent with what she was like."

Mrs Yeates said the thought of her daughter being found dead made her feel numb.

She said: "I sometimes picture her, if for some reason she collapsed or had been discovered, with all the snow and cold. I just can't bear the thought of it. I don't cope with it."

Mr and Mrs Yeates said their daughter and Mr Reardon had been due to visit their home in Ampfield, Hampshire, for Christmas tomorrow.

But they said Christmas would be "postponed" unless she was found.

Mr Yeates said: "Christmas is postponed as far as we are concerned. Everything is on hold and we can't celebrate anything.

"We want to think about Jo in our own way and hope and pray for her. If she's being held by someone, please let her go."

Mr Reardon, who had left for Sheffield before Miss Yeates returned from the pub, said yesterday: "I desperately want her back - I thought we would be together forever.

"She was my future. This Christmas was going to be our first together. I was going to spend it with her family, which is always a big deal for a boyfriend.

"We were both really happy in our jobs - we worked together and that's how we met."

Friends of Miss Yeates have set up the website helpfindjo.wordpress.com/ and an online campaign is running on both Facebook and Twitter.

People have also been putting up posters across Clifton appealing for information.

Police investigating the disappearance are examining CCTV footage and have also taken a phone and laptop computer from Mr Reardon.

Specialist officers have been searching the couple's flat, as well as the snowy Bristol Downs and Avon Gorge.

Detectives said that when Miss Yeates was in the Tesco Express she bought a Tesco Finest tomato, mozzarella and basil pesto pizza.

However, there was no trace of the pizza, the wrapping or the box in her flat.

Detective Chief Inspector Gareth Bevan, of Avon and Somerset Police, said: "I believe on the night in question Joanna got back to her flat and this would have been shortly after 8.30pm.

"We know from CCTV she went into Tesco's in Clifton Village at 8.30pm and when she was in Tesco she bought a pizza.

"I believe she went back to her flat and that is because we found within the flat her coat, her mobile phone and her keys but what we have not found is any evidence of this pizza or the box or the wrapping.

"I want to make an appeal, firstly to anyone who knows what's happened to Joanna or where she might be now.

"In particular, I want to appeal to anyone who knows where this pizza is now or where the box is or any information that might suggest where it is."