MADRID - Spain's top fashion show kicked off on Monday after causing a storm with its ban on skinny models and one well-known designer said he had to replace all the girls in his catwalk line-up.

Antonio Pernas, whose sixties-inspired collection marked the start of Madrid Fashion Week, said the rules banning overly-thin models had thrown his and others' plans into chaos.

"I had to change the whole lot in one day. Eighteen models. It gave us problems, but look, this industry sets an example to young women. We want to project a healthy image, so I'm not against the measures," Pernas told Reuters.

Organizers, under pressure from Madrid's regional government which sponsors the show, imposed restrictions on any model with too low a body mass index (BMI) -- a measure based on weight and height.

Regional President Esperanza Aguirre, who has argued young women copy the super-skinny look and might develop eating disorders, sat smiling at the end of the runway as tall, willowy girls in Austin Powers-style sunglasses strutted past.

The show's director Leonor Perez-Pita said some models last year "really were too thin" and welcomed the restriction that they must have a BMI of higher than 18.

"I think it's fantastic. They look beautiful. I don't want skeletons on the catwalk. Clothes look much better on a lovely girl than on a clothes hanger," she told Reuters.

The Madrid ban set off a storm in the fashion world, which has seen a trend for super-slim "size zero" models.

Britain's culture minister and Milan's mayor have already called for similar rules in London and Milan. The British Fashion Council had to scrap a photocall in London after a barrage of criticism for not following Madrid's lead.

Blanca Zurita, assistant to Spanish designer Fernando Lemoniez, said the weight debate threatened to overshadow months of design work.

She said the show's casting agency had been forced to make huge changes after a large number of models failed to make the weight.

But Ester Garcia, who runs the agency, said only one girl had not made the grade while another five chose not to attend.

Backstage, models seemed unfazed by the controversy.

"As long as it doesn't affect me I'm not too worried," said Caroline Duong who was rushing to get ready for Lemoniez's show.

"I do sport and I eat what I want though I do have to watch the chocolate a bit," the 1.82 meter (6-foot) tall model said.