Hollywood star George Clooney said Saturday that he is hopeful European audiences will respond to his light-touch wartime drama "The Monuments Men" after it got a mauling from US critics.

Clooney presented the picture at the 64th Berlin film festival about a real-life corps of middle-aged art experts who go behind enemy lines to rescue precious works from the Nazis, one day after it opened in US cinemas.

He said the film had been in the works for three years so the "amazing find" in Munich that emerged in November of a hoard of hundreds of missing artworks believed looted by the Nazis had been pure coincidence.

Initial feedback has been savage, with film industry bible Variety flaying the picture as an "exceedingly dull and dreary caper pic" while the New York Times called Clooney's direction "stolid" and "pandering".

Asked by an American reviewer whether he thought the movie, his fifth as a director, would get a "different" reception in Europe, where the film is set, Clooney said: "We'll see. This is our first city, the first screening was today. We hope good things."

"A near melee'"

The presence of the 52-year-old Clooney, who is arguably an even bigger star in Europe than in his native United States, touched off a frenzy at the festival.

A filled-to-the-rafters press screening, which had to be interrupted when a member of the audience required medical attention for a stroke, gave way to a near-melee to get into the subsequent news conference, as hundreds of fans thronged the streets to catch a glimpse of Clooney.

The filmmaker said he and his long-time collaborator Grant Heslov were inspired by an eponymous book of the little-known group of heroes, who managed to recover about five million works snatched by the Nazis across Europe.

"He and I had been doing rather cynical movies for quite some time and we'd been talking about doing something that was a little less cynical because we're not as cynical as the films we tend to make," said Clooney, who also worked with Heslov on "The Ides of March" and "Good Night, and Good Luck".

Clooney, who also stars in the movie, was asked repeatedly about the art-imitating-life aspects of the story given recent efforts to ensure the return of works to families whose property was stolen or extorted under the Third Reich.

"It's a story that's going to keep coming up because of course there's still an awful lot of art that's missing and will be found in lots of people's basements," he said.

"I'm glad it's part of the conversation again because it's a good conversation to have about the responsibility of giving back things that didn't belong to you."

Clooney was joined at the festival by co-stars Matt Damon, John Goodman, Bill Murray, Bob Balaban and Oscar-winning French "The Artist" star Jean Dujardin.

At the rollicking press conference, a Mexican journalist in her 50s asked what it was like contributing to "the erotic fantasies" of millions of women around the world, leading Murray to quip, "Ma'am, who's the question for?"

Clooney, who is known for his globe-trotting political activism, was asked by reporters about strife in Ukraine and South Sudan, drawing expressions of solidarity for people's "right to self-determination".

"The Monuments Men" appeared out of competition for the Berlin Golden Bear top prize, which will be awarded on February 15.