By Christine Kearney

NEW YORK (Reuters) - The unlikely image of a 92-year-old war bride screaming The Clash's "Should I Stay or Should I Go" into a microphone backed by an elderly chorus has already captivated live audiences around the world.

Now the film version is set to do the same.

"Young at Heart" documents the group of U.S. senior citizens belting out songs by Sonic Youth through to James Brown. The small-town act has been running for some 25 years but international fame is now at hand.

"A monster has been created," British filmmaker Stephen Walker joked in an interview about the film's rise.

It started as a 2006 British television documentary and became an audience favourite at the Los Angeles and Sundance film festivals in 2007 and 2008.

The opening sequence showing Eileen Hall, then 92, singing the 1982 hit from punk-rock group The Clash provided the inspiration for Walker when he first saw the group onstage in London in 2005.

"I was totally blown away," Walker said. "It was an amazing way to look at this song afresh. It becomes a song about love and death and not about relationships."

That led to Walker spending several months filming the group in Northampton, Massachusetts -- population 30,000 -- as members struggled to master lyrics from Sonic Youth's "Schizophrenia" to Allen Toussaint's "Yes We Can Can."

The film opens across the United States this week and, after scoring distribution deals, will soon open in France, Belgium, Switzerland, Germany, Japan and Australia.

AGING OUTCRY

Besides giving new meaning to lyrics from popular hits, the film is comedic and poignant as it explores friendship, old age and death.

It also addresses a society fed up with a "youth-obsessed and celebrity culture," Walker said.

"People are getting something extraordinary from this," Walker said about the standing ovations at preview screenings in the United States. "Somehow a nerve is being touched here."

Bob Cilman, the group's musical director for the past 25 years, said the popularity showed that audiences wanted to see more elderly people in the public spotlight, on stage or in film.

"Whether it is Australia, France or America, everybody is obsessed with youth and we fly in the face of that," said Cilman, 54. "People applaud it because (youth culture) is not what people want but it is what people are spoon-fed."

Stan Goldman, 78, shown in the film singing a duet of James Brown's "I Feel Good," told Reuters the group did not seek rock star status.

"In our wildest imaginations we never anticipated this," he said.

Pat Linderme, 77, said the goal was simple -- to sing and be happy.

"You get so caught up in your singing you forget your pain," she said.