CANNES (AFP) - The director of the Cannes Film Festival has apologised after a controversy blew up over women being denied access to the red carpet for not wearing high heels.

"We apologise," said Thierry Fremaux at a dinner at the famed Carlton hotel on Tuesday night.

But he sought to downplay the controversy that blew up on social media after reports that security guards had turned away females guests for wearing flats at a screening of Carol starring Cate Blanchett.

"There was perhaps a small moment of over-zealousness," he said, apparently referring to the guards.

The story, first reported by trade magazine Screen International, sparked hundreds of angry tweets and was described by actress Emily Blunt as "very disappointing".

"Everyone should wear flats to be honest. We shouldn't wear high heels anyway," she said at a press conference for her new film Sicario

The director of Sicario, Denis Villeneuve, joked that he and the film's co-stars, Benicio Del Toro and Josh Brolin, would "walk the stairs in high heels" later on Tuesday in solidarity at the red-carpet premiere. Sadly, the trio didn't.

The festival issued a statement on Tuesday in which it denied there was any official diktat on female footwear.

"Regarding the dress code for the red carpet screenings, rules have not changed throughout the years (tuxedo, formal dress for Gala screenings) and there is no specific mention about the height of the women's heels as well as for men's," the statement said.

There was further confusion because Screen International said it was initially directed to a press spokesman who told the magazine that high heels were "obligatory".

Festival organisers later told the magazine that the spokesman was misinformed.