Gila Almagor, the grande dame of Israeli drama, confirmed reports that the thriller is based on "Vengeance", a book about the Mossad intelligence service's assassination of Palestinian guerrilla chiefs in the 1970s that has been widely discredited.
The mission was mounted to avenge 11 Israeli athletes seized by Palestinian gunmen at the 1972 Munich Olympics and killed during a botched rescue effort. Several Mossad veterans have come out of the cold to question Spielberg's research.
But Almagor, who has been cast as the mother of a Mossad hit-man, called such quibbles "inappropriate, simply weird."
Good for image
"It is so important for him (Spielberg) that the film do what it should do for Israel," she said in a radio interview.
Asked if this meant the thriller would help Israel's image, Almagor said: "I believe that is the intention."
At least one of Almagor's fellow cast members has disagreed with her take on the screenplay for Spielberg's film.
"It's about how vengeance doesn't ... work - blood breeds blood," actor Daniel Craig told entertainment magazine Empire.
Spielberg, who is Jewish, is best known in Israel for his Holocaust epic "Schindler's List," which ends with Nazi death camp survivors starting new lives in the nascent Jewish state.
He has vowed the latest film will be sensitive.
"Viewing Israel's response to Munich through the eyes of the men who were sent to avenge that tragedy adds a human dimension to a horrific episode that we usually think about only in political or military terms," Spielberg has said in a statement.
Such sentiments raise eyebrows among Israeli security veterans who see the reprisals policy as best left undiscussed.
Israel has never admitted responsibility for the shootings, explosive booby-traps and commando raids that killed 10 Palestinians linked to the attack in Munich's Olympic Village.
The campaign included the 1973 killing in Norway of a Moroccan waiter mistaken for a wanted Palestinian guerrilla. Six members of the Israeli hit-team were prosecuted for murder.
Unverified details
According to "Vengeance," Israel left several of its agents to be hunted down and killed by Palestinians - an account not borne out by news reports nor the records of the Norway trial.
Author George Jonas said the book was based on recollections of an Israeli purporting to be a former Mossad assassin and that "certain details of the story were incapable of being verified."
Zvi Zamir, who headed Mossad in the 1970s, broke his silence upon hearing that the Spielberg film draws on "Vengeance."
"I am surprised that a director like him has chosen, out of all the sources, to rely on this particular book," the retired spymaster Zvi Zamir told an Israeli newspaper last week.