Many fans at volleyball's world championships in Tokyo were not watching the ball yesterday but staring at new women's outfits denounced by some players as sexist.

In a bid to make the sport more attractive to spectators, officials are using the month-long tournament to unveil major changes including a multi-coloured blue, yellow and white ball, instead of the traditional all-white ball.

Coaches are for the first time allowed to move freely along the sidelines during a match shouting instructions to players.

But the most controversial regulations cover the new strips - women must wear shorts only half as long as men players and are expected to wear shorts "tight in waist and length" and "cut in an upward angle towards the top of the leg".

The new regulations also "encourage", without ordering, women to wear a one-piece swimsuit-style outfit rather than the traditional shorts and top.

The changes are apparently an attempt to challenge the growing popularity of beach volleyball, but many women players are not happy.

"Soon only models will be allowed on the volleyball court," one South American player who did want to be named said. "How come our shorts have to be shorter than the men?"

A weekly magazine this week took up the theme with revealing photographs of a former top Japanese player-turned-model under the headline "semi-nude volleyball attack."

Federation of International Volleyball (FIVB) President Ruben Acosta defended the new look as being in step with the times and necessary to give the sport a more attractive image and to introduce consistency.

He said there had been a proliferation of strip lengths and styles that was not good for the sport.

"The image that the players project to the public is very important. If they don't project an image that people like to see then the public will not pay any attention," Acosta said.

The championships, involving the world's top 21 women's teams and 23 men's teams will be played over the next month in 15 Japanese cities, the first time since 1974 that the men and women's championships have been held in the same country.

The women's favourites are Cuba and Brazil while the men's title is expected to be decided between Italy and Yugoslavia.