Such is the secrecy that even the Israeli spymasters who commanded the reprisals after the Munich Games have been left out in the cold.

Five retired Mossad agents, all of whom served in key intelligence posts during the hunt for Palestinian resistance chiefs in Europe and the Middle East to avenge the slaying of Israel's 11 sportsmen, voiced surprise at hearing of the film.

"I know nothing at all about this project," a former Mossad director who declined to be named told Reuters.

Entertainment reports say the film, provisionally titled Vengeance and due to reach cinemas in December, is based on a book of the same name whose account of one of the most painful chapters in Jewish history has been widely discredited.

'Balanced film'

Spielberg spokesman Marvin Levy said the project had been comprehensively researched.

"This film has been built from many, many sources. One thing I can say is we expect this to be a balanced film," he said.

Steven Spielberg is famed for
making Hollywood blockbusters

Best known in Israel for Schindler's List, a Holocaust epic that ends with a pro-Zionist message, Spielberg was quoted as saying in a USA Today interview last week that the new film was a chance to explore his Jewish faith and fear of terrorism.

In the preface to Vengeance, author George Jonas declares himself a supporter of Israel. But according to at least one member of Spielberg's cast, Daniel Craig, the screenplay is a less-than-flattering portrayal of Israeli tactics.

"It's about how vengeance doesn't ... work - blood breeds blood," Craig told entertainment magazine Empire.

Israeli Prime Minister Ariel Sharon's office, which oversees Mossad and its archives, said it had received no request for assistance from any film production on Munich or its aftermath.

Deadly attack

It was not clear if help would have been forthcoming.

Israel has never formally claimed responsibility for the shootings, explosive booby-traps and cross-border commando raids that killed 10 Palestinians linked to Black September, the group that carried out the deadly attack in Munich's Olympic Village.

"That whole period is
too sensitive, even 30 years on. No one really wants to discuss it

ex-Mossad chief

The campaign included the 1973 slaying in Norway of a Moroccan waiter mistaken for Black September's leader. Six members of the Israeli hit team were prosecuted for murder.

Israel eventually paid compensation to the victim's family.

"That whole period is too sensitive, even 30 years on," said an ex-deputy Mossad chief. "No one really wants to discuss it."

But Zvi Zamir, who headed Mossad in the 1970s, broke his silence after Vengeance, purporting to be an expose based on the confessions of a Mossad ex-assassin, was first published.

Controversial claim

According to the book, Israel largely abandoned its agents mid-mission in Europe, where several were hunted down and killed by Palestinian counter-espionage teams - an account borne out neither by news reports nor by the protocols of the Norwegian trial.

Zamir told the New York Times in 1984 that the version of events in Vengeance was "not true" but did not elaborate.

While standing by his source, Jonas admitted that "certain details of the story were incapable of being verified".

Jonas's agent Linda McKnight told the Wall Street Journal last year that Universal Pictures, which is co-producing the film with Spielberg's Dreamworks, had exercised an option to make a film based on the book.