Hollywood veterans Steven Spielberg and George Lucas have sparked a debate by warning of an "implosion" of the traditional movie industry, amid soaring budgets and competition from cable TV.

Opening a new department of a new film school in Los Angeles, "E.T." and "Jurassic Park" legend Spielberg revealed that he almost failed to get his Oscar-winning political biopic "Lincoln" into theatres last year.

"Star Wars" icon Lucas warned that access for films to be released into theatres is "getting smaller and smaller" and said cable television has become much more adventurous.

"I think eventually the 'Lincolns' will go away and they're going to be on television," Lucas said at the opening of a new interactive media building at the University of Southern California (USC)'s School of Cinematic Arts.

"As mine almost was," Spielberg interjected at the Wednesday event, according to the Hollywood Reporter. "This close -- ask HBO -- this close."

Lucas added: "We're talking 'Lincoln' and 'Red Tails' (a 2012 film which Lucas executive produced) -- we barely got them into theatres. You're talking about Steven Spielberg and George Lucas can't get their movie into a theatre."

Spielberg said some young filmmakers' ideas were "too fringe-y for the movies," adding: "That's the big danger, and there's eventually going to be an implosion -- or a big meltdown.

"There's going to be an implosion where three or four or maybe even a half-dozen megabudget movies are going to go crashing into the ground, and that's going to change the paradigm," he said.

Films with budgets of $200 million are increasingly common, and a number have failed in recent years, including last year's "John Carter," which led to the departure of a top Disney boss.

Hollywood A-lister Will Smith's latest movie "After Earth," with an estimated budget of $130 million, flopped badly earlier this month, making a less-than-stellar $27.5 million on its opening weekend.

The trend towards making "edgier" films for cable TV rather than theatre was highlighted recently by "Behind the Candelabra," Steven Soderbergh's biopic of flamboyant entertainer Liberace starring Michael Douglas and Matt Damon.

The film's gay theme prompted mainstream Hollywood to shy away from financing the picture. As a result, Soderbergh turned to the US cable TV giant HBO, meaning it cannot be an Oscar contender.