Los Angeles - The Curious Case of Benjamin Button, starring Brad Pitt as a man born old who grows younger, emerged Thursday as the Oscar front-runner when it nabbed a leading 13 nominations for the most prestigious prizes in the US film world.

The Mumbai-based movie Slumdog Millionaire was another strong contender, earning 10 nods, while Milk, which stars Sean Penn as the first openly gay politician in the US earned eight nominations.

All three were nominated for best movie along with Frost/Nixon about a series of revealing interviews of the former US president Richard Nixon, and The Reader, about a young man's romance with a female Nazi guard.

The five films competing for the best foreign language film were the acclaimed Israeli animated documentary Waltz with Bashir, about the country's invasion of Lebanon in 1982, as well as the German film the Baader Meinhof Complex, Revanche from Austria, The Class from France, and Departures from Japan.

Competing for best director were Slumdog's Danny Boyle, David Fincher for Benjamin Button, Ron Howard for Frost/Nixon, Gus Van Sant for Milk, and Stephen Daldry for The Reader.

The best actor nominees were Richard Jenkins (The Visitor), Frank Langella (Frost/Nixon), Sean Penn (Milk), Brad Pitt (The Curious Case of Benjamin Button) and Mickey Rourke (The Wrestler).

The best lead actress nominees were Anne Hathaway (Rachel Getting Married), Angelina Jolie (Changeling), Melissa Leo (Frozen River) Meryl Streep (Doubt) and Kate Winslet (The Reader).

Exactly one year to the day, Heath Ledger earned an Oscar nomination for best supporting actor for his performance as the Joker in the Batman drama The Dark Knight. The movie earned seven nominations, but no others in the major categories.

Benjamin Button was also nominated for art direction, cinematography, costume design, film editing, makeup, original score, sound mixing, visual effects, and adapted screenplay.

Slumdog's other nominations included three for music and songs as well as adapted screenplay sound editing, sound mixing and cinematography.

The Oscars will be presented in Los Angeles on February 22. (dpa)