Ridley Scott-directed Alien films are, it seems, a bit like buses: you wait 30 years for one, and then two come along at once.

The veteran British film-maker, who was at the LA press junket for his new film Robin Hood, told Collider.com that he was planning a brace of 3D prequels to his classic 1979 slasher-in-space flick.

"It'll be two," revealed Scott. "Prequel one and two, then Alien 1." Asked if he would shoot the two films back-to-back, he responded: "At the moment I'm just trying to get the first one out."

Scott announced in July that he would be directing a prequel to Alien, but the second film is a new development. He also said that the screenplay for the first film was into its fourth draft, with a release date planned for late 2011 or 2012. Finally, Scott said he planned to shoot the films in dazzling brightness to help the 3D process, before darkening the screen in post-production to suit the franchise's sombre tone.

Scott had originally intended to be a producer on the Alien prequel, with his protege Carl Rinsch, a TV adverts director, taking the reins. But following reports that studio 20th Century Fox was unhappy with the idea of an untried director, it was announced that the Gladiator film-maker himself would be behind the cameras.

The new films, as announced last year, will be set before the events of Scott's 1979 film, in which the crew of a commercial towing ship respond to a distress signal from an empty ship, only to discover too late that the signal was meant to warn them. Three sequels and two Aliens Vs Predator spin-offs followed, but only James Cameron's 1987 Aliens lived up to the original. The prequels will be Scott's first science-fiction project since Blade Runner in 1982.