LONDON (Reuters) - Robert Redford said on Wednesday that the future of London's Sundance film and music festival was by no means certain, as he launched the British version of an event that aims to boost interest in independent film.

Last year was the first time that the U.S. actor-director had ventured outside the United States with a version of the Sundance Film Festival, the world's leading independent film festival, that he set up in Park City, Utah, 35 years ago.

Redford said last year was "a toe-in-the-water experiment" and had been successful enough to repeat, with this year's line-up including the U.S. rock band the Eagles and the Canadian musician and performance artist Peaches.

But he was noncommittal on its future.

"It is hard to declare a length of commitment until you let it play out and see how it goes," Redford told a news conference before the festival at London's O2 venue from April 25-28.

Last year he told reporters that he hoped Sundance London would prove a success with audiences and allow him to expand the festival to other parts of the world as a counterweight to the Hollywood blockbusters that dominate cinemas globally.

When asked on Wednesday if he still planned to take Sundance to other countries, he replied with a curt "No".

Redford, 75, set up the Sundance Institute in 1981, which led to the film festival, to encourage emerging and aspiring filmmakers working outside Hollywood's major studios. But he said the sector continued its uphill battle.

"Independent film has always had to struggle for a place in the universe ... overall mostly due to the economy it is difficult," he said.

A slate of 119 films from 32 countries were shown at Sundance in January, and 21 U.S. and British films were selected for London as well as musical performances by Peaches and indie rock band British Sea Power. The Eagles are not performing.

This year's films include nine documentaries, which focus on a variety of themes ranging from a struggling British dairy farmer in "The Moo Man", the ill-fated 2008 K2 climb in "The Summit", and the "History of The Eagles Part One".

Others British premieres include Michael Winterbottom's "Look of Love", in which Steve Coogan plays porn king Paul Raymond; Lynn Shelton's comedy "Touchy Feely" about a massage therapist; and Barbara Kopple's documentary "Running From Crazy" about Mariel Hemingway.

Redford said he was particularly fond of documentaries and proud of the advances made in this genre in recent years, which he attributed to encouragement by the independent film sector.

"We kept pushing documentaries forward so that now in our festivals they take up pretty much the same space as others films do," he said.