The party also called for all adverts to carry information about the extent to which they have been digitally altered as part of a clampdown on "unrealistic" images of women.

The move was backed by the Liberal Democrat conference in Bournemouth after Dumbartonshire East MP Jo Swinson told activists the practice was "dishonest, harmful and has to change".

The proposals, in a paper on Women's policy, would require all advertisements to declare the extent to which digital retouching technology has been used to create "overly perfect" images of women and men.

Extensive retouching would be banned in adverts aimed at under-16s, and the party pledged to work with the industry and the Advertising Standards Authority over the plan.

The use of retouching to remove blemishes and alter body shapes of models was blamed for an increase in the number of people with eating disorders.

The policy paper also called for names to be removed from job application forms to prevent discrimination on the grounds of gender or race and would require every late night train to include a safe "guard's carriage".

Ms Swinson said: "This paper does not confine itself to domestic violence and equal pay.

"We are raising issues that don't usually make it onto the political agenda, like body image and media pressure.

"I make no apology for that. Because we listened to women and this paper is the result."

She condemned Labour's results in improving equality, blaming Business Secretary Lord Mandelson for blocking Labour Deputy Leader Harriet Harman's efforts.

"Whatever Harriet might want to do, Mandy won't let her," she said.

The airbrushing move was opposed by another Scottish activist, Bernard Salmon from Inverness East, Nairn and Lochaber, who said it was "unworkable" and urged the party to work on achieving cultural change rather than creating new regulations.

His effort to block the proposal was overwhelmingly rejected by the conference.

Neil Fawcett (Oxford East) told the conference the move was necessary because "if the rates of cancer were rising at the rate of eating disorders, this would be at the top of the political agenda".

The conference also backed calls for greater media coverage of women's sport and for netball to be included at the 2012 Olympic Games in London.

After the motion was carried, Ms Swinson said: "Women face pressure from all directions these days. Hit hard by the recession, trying to juggle family commitments with work and home life, and bombarded with adverts that contain completely unattainable images that no-one can live up to in real life.

"Despite great strides forward in equality, women still get paid less than men, and generally still end up taking more responsibility for childcare and looking after elderly relatives. This can be hugely rewarding, but combining this with a job can seem almost impossible.

"There's a lot the Government could do to give a helping hand. Making employers check for pay discrimination would help women get the money they deserve. Providing 20 hours per week free childcare would allow parents to make real choices about returning to work. And it would be nice to inject some realism into the media's portrayal of women, instead of the suggestion that nothing less than perfection will do."