Media playback is unsupported on your device Media caption George Lucas signs away his Star Wars empire to Disney's Robert Iger

Disney is buying Lucasfilm, the company behind the Star Wars films, from its chairman and founder George Lucas for $4.05bn (£2.5bn).

Mr Lucas said: "It's now time for me to pass Star Wars on to a new generation of film-makers."

In a statement announcing the purchase, Disney said it planned to release a new Star Wars film, episode seven, in 2015.

That will be followed by episodes eight and nine and then one new movie every two or three years, the company said.

The last Star Wars film was 2005's Revenge of the Sith, and Disney said it believed there was "substantial pent-up demand".

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James Burns, founder of fansite Jedi News in the UK, said: "It is fantastic that we are going to be seeing more Star Wars films as George Lucas has said many times that there wouldn't be any more."

Disney will pay about half in cash and half in stock, issuing 40 million Disney shares in the transaction.

The deal follows Disney's acquisitions of Pixar studios for $7.4bn in 2006 and Marvel comics for $4.2bn in 2009.

"Our valuation of Lucasfilm is roughly comparable to the value we placed on Marvel when we announced that acquisition in 2009," Disney said, adding that the valuation was almost entirely driven by the Star Wars franchise.

Transition

George Lucas launched Lucasfilm in 1971 and the first Star Wars film was released in 1977.

"For the past 35 years, one of my greatest pleasures has been to see Star Wars passed from one generation to the next," Mr Lucas said.

"I've always believed that Star Wars could live beyond me, and I thought it was important to set up the transition during my lifetime."

Mr Lucas will continue as a creative consultant.

Kathleen Kennedy, currently co-chairman of Lucasfilm, will become president of the firm and will be the executive producer on the new Star Wars films.

Media playback is unsupported on your device Media caption Critic on new Star Wars: "My heart sinks"

She worked on the Jurassic Park and Back to the Future franchises and co-founded Amblin Entertainment with Steven Spielberg.

When the later Star Wars films were released in the 1990s and 2000s, although they did well at the box office, they were generally not well-received by fans.

But Josh Dickey, film editor at Variety magazine in LA, said that Disney was a "great fit" to update Star Wars.

"They're so good at branding and brands. They're so good at working with existing intellectual property and making it resonate with fans and marketing it very well," he told BBC World Service radio.

"They're not as good at creating original content, except for their Pixar division.

"I think if you bring together the minds from Pixar [and] the minds from Disney, the news that Disney is going to reboot Star Wars was a lot more exciting to fans than just 'there's gonna be another Star Wars'."

Media playback is unsupported on your device Media caption Jedi fans "really, really excited"

Surprise

Lucasfilm is also the production company behind the Indiana Jones franchise, and fantasy films Willow and Labyrinth.

Michael Corty, analyst at Morning Star, said Disney's deal was clearly part of a pattern in buying new franchises.

"Pixar was the first big one, then Marvel, and now this one here," he said.

"Because Lucas is private, I would assume most investors would be surprised."