Australian director Bruce Beresford says Russell Crowe would be too old to play a lead role in his upcoming film about the Vietnam War's Battle of Long Tan.
But Oscar winning Crowe could play an officer, if he were interested in getting involved in the project.
"Strictly speaking, Russell is too old (for the film)," said the acclaimed director, who next week will deliver the National Film and Sound Archive's Langford Lyell Lecture.
"The problem with war movies characteristically is that all the guys playing the soldiers are too old.
"I certainly would rather cast people who are the right age for the parts - that was a battle fought by very young guys."
Beresford has worked with some of the biggest names in Hollywood, including Morgan Freeman, Sharon Stone, Ethan Hawke, Sean Connery, Glenn Close and Cate Blanchett.
He said having A-list names attached to a project was vital in the very competitive film business.
"If you don't have names, it is almost impossible (to get a film made)," said Beresford.
"Long Tan would probably appeal to Russell's patriotism but I don't know if that would work."
Long Tan, to be produced by Martin Walsh, will have a budget of up to $42 million, depending on casting and production specifications.
Eighteen soldiers died on August 18, 1966, as a tiny force of just 108 men fought off some 2,500 Viet Cong and North Vietnamese troops in a rubber plantation, inflicting hundreds of enemy casualties.
Beresford is currently researching and writing the script with production likely to begin early next year in Sydney and north Queensland.
"I have got a lot of research to do," said Beresford, whose film credits include Driving Miss Daisy, Paradise Road and Breaker Morant.
"I have just been up in Queensland talking to eight interesting guys who were in the battle."
Beresford is attached to three other films likely to go ahead in the next few years.
He is to direct the Norah Ephron-penned Flipped, about the relationship of two kids who lock horns at age seven and share their first kiss at 13.
Beresford's also working on a film adaptation of Oscar Wilde's play A Woman of No Importance, with Lindsay Lohan, Sean Bean and Annette Benning believed to be attached.
And Beresford said he had been working with controversial British author Geoffrey Archer on his screenplay, Walking Off The Map.
"It is a wonderful screenplay about George Mallory, the Everest climber," he said.
"I have been working on that with Jeffrey for about two years. It is a very very good script he wrote when he was in jail."
Meanwhile, Beresford said he would focus on music in films when he delivers the annual Langford Lyell Lecture in Canberra on October 4.
"Film music tends to somewhat irritate me," he said.
"It gets in the way of all the sound effects and everything."