By Bob Chaundy BBC News Profiles Unit

On the eve of her 100th birthday the German filmmaker Leni Riefenstahl has released a new picture . The controversy surrounding her has ensured that this is her first film for half a century. His plane appears from behind the clouds like an eagle swooping across the sun, its shadow flitting across the rooftops, heralding a momentous arrival.

Adolf Hitler is flying in from his own Eagle's Nest to attend the 1934 Nuremberg Rally.

This enticing scene opens Leni Riefenstahl's Triumph of the Will which depicts in Wagnerian glory the whole spectacle of this piece of Nazi theatre.

Hitler was captivated by her in The Blue Light

With pioneering techniques involving cranes, tracking rails, a mass of cameras, all in harness with a keen sense of detail and beauty, Triumph of the Will and her subsequent portrayal of the 1936 Olympics, Olympia, are regarded by many as among the greatest documentaries ever made.

The influential New Yorker film critic, the late Pauline Kael, regarded Riefenstahl as "one of the dozen or so creative geniuses who have ever worked in the film medium".

But it is because of her genius, that Leni Riefenstahl will always remain a controversial figure.

Art not politics

For, one of the many reasons behind the staging of the Nuremberg rallies was, in the words of historian Michael Burleigh, author of the recent The Third Reich, "to distract from the grim underside of a police dictatorship".

Triumph of the Will, through its powerful yet disturbing glorification of the Nazi ideal was, "a propagandist exercise so definitive that it never needed to be repeated".

Leni Riefenstahl has protested consistently down the years that she was only ever concerned with art and not politics.

One of the greatest ever film directors

"I was only interested in how I could make a film that was not stupid like a crude propagandist newsreel, but more interesting", she told BBC News Online. "It reflects the truth as it was then, in 1934. It is a documentary, not propaganda."

Originally a dancer, injury had steered her towards acting and she became one of Germany's most famous film stars of the 1930s.

She might easily have been lured to Hollywood like her great rival, Marlene Dietrich. But having performed in a host of highly popular mountain adventures that showcased her great beauty and athleticism, she switched to directing.

In those days, such a move was almost unheard of for an actor, let alone an actress.

Commissioned by Hitler

Hitler had been captivated by her performances in The Blue Light and The Sacred Mountain and chose her to film for him. He instructed his propaganda chief, Josef Goebbels, to give her almost unlimited resources.

For Olympia, she even had lifts installed in the swastika-bearing flagpoles in order for a cameraman to shoot vertical tracking shots.

Her films glorified the Third Reich

Leni Riefenstahl maintains that she was swept along by the tide of enthusiasm for Hitler and that she was unaware of the bad things he was doing until too late.

She has contested more than 50 libel suits and has won all bar one. She has claimed that Olympia glorified the human form for purely aesthetic reasons and was not, as her critics claim, eulogising the Aryan master race.

She points to the film's particular concentration on Jesse Owens, the black American athlete whom Hitler famously snubbed.

Nevertheless, despite being cleared by two denazification tribunals, and despite never having been a member of the Nazi party, Leni Riefenstahl could find no more work in films.

Still pictures move

Instead, she turned to photography, producing highly acclaimed portraits of members of Sudan's disappearing Nuba tribe.

Once again, she had celebrated the human form in a way that the American writer Susan Sontag has described as "consistent with the ideas of her Nazi films".

One of her photographs of the Nuba tribe

Chronic back-pain in her 70s inspired Leni Riefenstahl to take up scuba diving, a pursuit less stressful on the back and less likely to provoke controversy, fish not being noted for their political connotations.

"Better than Cousteau", has been one comment so far on Impressions Under Water, a compilation of more than 200 dives she has made over the past 25 years.

In the flesh, Leni Riefenstahl has a charisma that exudes from a passion for everything she turns her hand to.

And, in her long lifetime, she has turned her hand most successfully to being a dancer, actress, director, writer, photographer and now, underwater filmmaker.

Hollywood on the case

It's a small wonder that the Hollywood actress/director Jodie Foster is determined to recount Riefenstahl's story on film despite protests from the Jewish lobby.

Although the script has reportedly not yet been written, Foster claims her movie will not be a whitewash.

At the 2000 launch of her pictorial biography

"What interests me here is the responsibility of artists", she has said. "Her story is an extremely important morality tale for future generations."

Leni Riefenstahl, by any standards, is a most extraordinary woman.

But even though her films for Hitler constitute but a tiny fraction of her lifetime achievements, her name will always be raised in the debate about the relationship between art and morality.