The sequel to 'Avatar' is to begin shooting later this year, according to Sigourney Weaver.

Sigourney Weaver

Sigourney Weaver

The 67-year-old actress, who starred in the James Cameron-directed original in 2009, has revealed preparations have already started to make the much-anticipated follow-up movie.

She shared: "We're starting! We're starting training, and we're starting - hmm, I probably can't say anything. We will be actually shooting it by the fall."

The original 'Avatar' movie grossed $2.7 billion at the global box office, and received widespread praise from movie critics.

And Sigourney has reassured fans that the sequel won't be a disappointment to them, insisting the new sci-fi movie will be worth the lengthy wait.

She told The Hollywood Reporter: "I'm telling you, these scripts are so amazing, I'm not worried about [disappointing fans] at all.

"Am I worried about how we're going to bring them to life? Yes, because they're so ambitious. They're so worth it. They're well worth waiting for. I'm not worried about that at all. We're trying to get it done as quickly as possible."

Meanwhile, James Cameron previously claimed he is not worried about the delays to the release of the next 'Avatar' movie.

The director intends to make four sequels in total, but there have been significant delays to his original plans, meaning fans have been kept waiting for years for the next instalment in the franchise.

But James said: "The important thing for me is not when the first one comes out but the cadence of the release pattern.

"I want them to be released as close together as possible. If It's an annual appointment to show up at Christmas, I want to make sure that we're able to fulfil on that promise."