Edie Falco has joined the 'Avatar' franchise.

Edie Falco

Edie Falco

The 55-year-old actress is set to star in James Cameron's four upcoming sequels to the hugely successful 2009 sci-fi movie as General Ardmore.

Although plot details are being kept under wraps, 'The Sopranos' star's character has been described as the leader of the fictional Resources Development Administration, the largest single non-governmental organisation in human space.

The official 'Avatar' Twitter account announced: "We are thrilled to share that Edie Falco is joining the #AvatarFamily as General Ardmore, the Commander in charge of the RDA's interests in the Avatar Sequels! (sic)"

The original film is set on the alien world of Pandora inhabited by the Na'vi, beings who appear primitive but are highly evolved, as the planet's environment is poisonous, human/Na'vi hybrids, called Avatars, must link to human minds to allow for free movement on the planet.

Jake Sully (Sam Worthington), a paralysed former marine becomes mobile again through one such Avatar and falls in love with a Na'vi woman (Zoe Saldana), however, he is drawn into a battle for the survival of her world when the RDA threaten to destroy it.

'Nurse Jackie' star Edie was welcomed to the cast by Cameron, 64, who insisted the actress is "one of the greats".

The director told his 640,000 followers: "Edie Falco is one of the greats - I can't wait to watch her kick some ass on the big screen."

Cameron revealed, the first movie will be released in 2020, followed by the other three in 20121, 2024 and 2025.

The first 'Avatar' film, released in 2009, still remains the highest grossing movie at the worldwide box office, raking in as much as $2.79 billion.