Threesomes are too "complicated" to work in real life, Woody Allen and Penelope Cruz said on Saturday as they unveiled 'Vicky Cristina Barcelona', a sex romp featuring a hilarious menage a trois.

The movie, which is screening out of competition at the Cannes film festival, drew big laughs and applause at a packed press preview late on Friday ahead of its red-carpet premiere later on Saturday.

Cruz appears as a tempestuous Spanish woman who is still drawn to her ex-husband Juan Antonio, a mysterious painter played by her off-screen partner, Oscar winner Javier Bardem.

Juan Antonio, however, has become enamoured with two American women spending the summer in Barcelona — one daring (Scarlett Johansson), the other repressed (Rebecca Hall).

The result is a series of love triangles — the most prominent of which leads to passionate onscreen kiss shared by Johansson and Cruz and the two women later landing in bed with Bardem.

The trio lives together in an Eden-like bliss for weeks until one of the women gets restless.

Bardem missed Saturday's premiere due to a family problem while Johansson was kept away because of scheduling conflict, Allen said.

Balancing two partners

Asked whether he had scripted a private fantasy of sex with two women, Allen quipped: "It's hard enough to get one person."

The 72-year-old director said trying to keep in balance between two partners would be daunting.

"In real life, most people could not survive that kind of situation in any serious way because it's too complicated and has too many emotional ramifications," he told reporters.

"In a film, you can do it because I'm dealing with larger-than-life characters."

In a typically surreal question for a Cannes press conference, a reporter claiming to be from Uzbekistan asked whether Allen had any plans to make a film in her country where "we have many women in the family as wives".

"The thought had never occurred to me actually," Allen deadpanned. "I'm a fearful traveler."

Pure fantasy

Cruz agreed a lasting three-way relationship was pure fantasy.

Her character, she said, "has a very peculiar way of doing things... I understand her, but I would probably make different choices."

In the film, Juan Antonio catches a glimpse of the beautiful tourists at a restaurant and promptly makes a brazen proposition for the two to join him for a weekend of sightseeing and sex in his provincial hometown of Oviedo.

The uninhibited Cristina, played by platinum-dyed Johansson, is game but her friend Vicky, who is engaged to Brad, a dull Wall Street type back in New York, only reluctantly comes along.

When Cristina and Juan Antonio's liaison turns into more than just a fling, she moves in with him. But the arrival on the scene of Maria Elena, Juan Antonio's fiery ex-wife, throws everyone for a loop.

Fight with relish

Cruz and Bardem dive into their scenes with relish and their fights in Spanish and English drew some of the biggest laughs.

Allen wrote the script with Cruz in mind. She called him a "genius" who allowed her and Bardem to switch languages as it fit the scene.

"But in English I was too afraid of changing anything because you don't change a Woody Allen line," she said.

The tone of the film is light as air but the story is filled with wry vintage-Allen insights about love, art and the point of existence.

Allen's last feature at Cannes, the London-based drama 'Match Point' that screened in 2005, revived a career many critics had written off.

The festival runs to 25 May.

AFP