The Star Trek filmmaker, who is taking the directing reins on the upcoming instalment of George Lucas' sci-fi series, admitted that work is now under way for the movie, reported The Wrap.

"We're working really hard and we've got our script and we're in deep prep. Full steam ahead," he said at a Television Critics Association panel.

JJ wouldn't be drawn into the length of the film, and remained tight-lipped over the casting.

He admitted he has met with Breaking Bad star Jesse Plemons, but played down the rumours about the actors he is said to have approached for roles.

"He is one of the actors that we've talked to," the director said. "But it's not often that I read about actors that I'm going to be meeting. I get to read articles about actors who are going to come in.

"And so I get to see someone and say, 'Oh, I read that I was going to see you!'... It's usually agents talking to people about what's happening. It's a lot of noise."

JJ added: "It's sweet because it shows that there's an interest in this movie that we all obviously know is there. But it is an incredible thing to see how many crazy things get thrown out that people then often write commentaries about. How happy they are, how disappointed they are about something that is completely false."

Michael Fassbender, Hugo Weaving and Girls star Adam Driver are the latest batch of names linked to Star Wars: Episode VII, while Mark Hamill, Harrison Ford and Carrie Fisher are tipped to reprise their original roles.

The film will be released in December 18, 2015.

The Oscar-winning actress admitted that she initially declined the part of the cancer sufferer and sharp-tongued matriarch in John Wells' big-screen adaptation of Tracy Letts' Pulitzer Prize-winning play, because she had doubts about immersing herself into the character.

"I said no, I really did. But they dragged me in, kicking and screaming," she said.

Julia Roberts, Juliette Lewis, Ewan McGregor and Benedict Cumberbatch also star in the dysfunctional family drama, which focuses on the relationships between the family members after they are reunited, following a crisis.

"I said no because who really wants to sign up to know what it feels like to have mouth cancer and children that hate you and a husband who'd rather kill himself than be in your presence, and chemotherapy, pills and misery and a horrible past?" Meryl continued.

"To crawl into that head, that heart, I thought, 'Ah'. Because part of that pain is, you realise as you get older, these things cost you more in a weird way. You carry them home, you feel you bleed more easily with it."

The 64-year-old added: "Having said that, it's a great part and as an actor, I thought, 'Hell'. Such a cast. How could I not?"

Meryl, who has received a number of nominations for her performance, will face Dame Judi Dench, Cate Blanchett, Sandra Bullock and Amy Adams for the best actress award at the Oscars on March 2.

-August- Osage County opens in cinemas on January 24.