07/22/2008 AT 05:10 PM EDT
A posthumous Oscar for Heath Ledger
for his Joker performance?
"I would vote for him," his Dark Knight
cstar Maggie Gyllenhaal told reporters Monday at the film's London premiere.
Gyllenhaal, 30, said of Ledger's Oscar prospects that the "degree of difficulty should be incorporated into the award."
"To be that incredible in a movie that's this huge, that's about so many things, is really an accomplishment," she said. "In a way I feel funny thinking about the Oscars when he isn't alive, but at the same time I'm a member of the Academy and I would vote for him."
Gyllenhaal – who replaced Katie Holmes
in the role of Assistant District Attorney Rachel Dawes – spoke to reporters while her fiancé Peter Saarsgard watched from a few feet behind.
She said of Ledger's performance: "In order to be a good actor you have to find a place where you are free, but it's very unusual to be absolutely free in the way that he was in this movie It was inspiring working with him."
At the premiere – which featured a 2.5 ton replica of the Batmobile, shooting flames – fans carried signs and banners campaigning for an Oscar for Ledger.
Michael Caine, who plays Batman's butler Alfred, told reporters he "would pay good money" to see a performance that could top Ledger's for the Oscar. Previously Caine said Ledger was worthy of nomination