Oscar-winning actress Halle Berry was caught off-guard by the Cannes Film Festival's updated dress code and had to switch her outfit choice last minute, she told journalists on Tuesday.

Under the rules, nudity is not allowed on the red carpet, and "voluminous outfits, in particular those with a large train," that block the way for other guests and complicate theatre seating are also no longer permitted.

Organisers said they could deny red carpet access to those who do not respect the rules.

"I had an amazing dress by Gupta to wear tonight, and I cannot wear it because the train's too big," Berry, who is a festival jury member this year, said at a news conference.

"I had to make a pivot. But the nudity part I do think is probably also a good rule," added the U.S. star who won an Oscar for the 2001 film "Monster's Ball."

In recent years, guests and celebrities on the red carpet have been pushing the limits of the festival's dress code with giant trains, sheer dresses and nipple-baring outfits.

Kanye West and his wife, Bianca Censori, caused a stir at the Grammy Awards red carpet in February when Censori dropped an oversized coat to reveal a sheer dress with nothing underneath.

In addition, the code now explicitly allows for elegant shoes without a heel on the red carpet, a move welcomed by jury president Juliette Binoche.

"On the heel side, I think it's a very good idea, by experience," said the French film star on Tuesday.