Victoria Beckham "close to collapse"

Victoria Beckham's grueling work schedule and her desire to make it big in the fashion industry remain so intense that husband David and her closest friends fear the pint-sized star is "close to collapse".

"Victoria has been running on empty the last months and is very tired," says a source close to Victoria - who finished the exhausting  Spice Girls world tour last month. "The tour has completely drained all the energy out of her, as it did all the other girls, but on top of her Spice Girls commitments, Victoria has continued to invested masses of energy into her fashion career."

Last night, the 33-year-old singer judged the final of Project Runway - after pal Heidi Klum asked her to be a guest panelist on the season finale of her reality fashion design show.

Adds the source: "Everyone is worried she might keel over.

"Victoria kept saying how exhausted she was [during New York fashion week] and there were moments backstage when she had to stop and sit down or lean against a wall - because she felt wobbly.

"She has been racing around so much and sometimes it will get to 9pm and she will realize she hasn't eaten anything and only drunk green tea and water all day.

"During the [Spice Girls] tour, she was surviving on an average of five hours' sleep a-night and she often has to suck her cheeks when she's in public - so that she's not photographed yawning.

"Victoria has also been complaining that her skin has been playing up and she feels her hair is lank and lifeless."

Despite the worrying signs, sources tell Britain's Grazia magazine that Victoria is delighted by the fact her fashion career is taking off - earlier this year, she became the face of Marc Jacobs - and she is keen to capitalize on the success of her jeans and sunglasses range.

But friends fear that Victoria's marriage is also on the line - as well as her health.

Adds the source: "Victoria's obsessions with  becoming a world acclaimed fashion designer and launching more fashion lines could cause friction between her and David.

"She is finally being taken seriously in the fashion industry; and wants to make the most of her success.

"David is concerned that she isn't taking enough time to relax; and that her career doesn't eclipse the rest of her life.

"The last thing anyone wants is for Victoria to make herself ill."

But friends fear Victoria is determined to push herself even further - and is even reportedly planning to open her own fashion store in the US.

"She’s very opinionated about fashion, which I love," says Project Runway host Heid Klum of her budding fashionista pal. "I like when someone says their peace about what they think instead of being wishy washy. I like her very much."