Oscar best director winner Ang Lee poses with his Oscar at the 78th annual Academy Awards in Hollywood, March 5, 2006.  [Reuters]

Oscar winner Ang Lee has approached Hong Kong's Tony Leung Chiu-wai about appearing in his upcoming spy thriller, "Lust, Caution," Lee's assistant said Sunday.

"It hasn't been confirmed yet. We have approached him, but we won't finalize all the characters until we choose a female lead," the director's assistant, David Lee, told The Associated Press in a phone interview.

"We haven't decided on a female lead," David Lee said.

Tony Leung

"Lust, Caution," based on a novel by Eileen Chang, marks Ang Lee's return to Chinese-language film after several English-language productions including "The Hulk" and most recently, the gay romance "Brokeback Mountain," for which he won best director Oscar this year.

Observers are closely watching Ang Lee's casting choices to see if he will produce another female star. Lee's box office hit "Crouching Tiger, Hidden Dragon," helped propel Zhang Ziyi to stardom. Zhang went on to star in Hollywood movies like "Rush Hour 2" and "Memoirs of a Geisha."

Zhang Ziyi

Lee has reportedly said he wants to cast an actress from Taiwan to boost the island's struggling film industry.

David Lee said filming for "Lust, Caution" will begin in the fall in Shanghai and Hong Kong.

Tony Leung Chui-wai won best actor at Cannes in 2000 for his role in Wong Kar-wai's romance "In the Mood for Love." Leung also appeared in Wong's gay love story "Happy Together" and the crime thriller "Infernal Affairs," which has been remade by Martin Scorsese as "The Departed."