Danny Boyle has revealed that the long-awaited sequel to Trainspotting will start shooting next summer, Digital Spy reports.

The film could even be released as early as 2016 should everything go smoothly and all the actors' schedules align.

Boyle has already said that all four original leads - Ewan McGregor, Jonny Lee Miller, Robert Carlyle and Ewen Bremner - are interested in returning.

"They only get this little window off, so either you wait for the contract to run down, which could be as late as three years, or you kind of try and do it in this window," he told The Hollywood Reporter.

"The actors were understandably worried about its reputation and not wanting to let people down or to just be cashing in.

"So actually the script, which John [Hodge] has written, has been put under a very fierce spotlight by everyone, and it's a good one."

The follow-up is to be based partly on Irvine Welsh's Trainspotting book sequel Porno, but the Slumdog Millionaire director insisted that the film will be "its own thing".

"Everyone's attitude is that it'll be an honourable addition and an interesting addition to the original film," he explained. "We're very positive that we believe it can happen and it's coming true."

Boyle also said that the budget would give them more freedom when making the film, despite being much more than the original's $2 million budget.

"We're doing it for less than $20 million, and that'll give us control of the film so we can make the film we want to make," he added.

"Although we could have raised a lot more money for this, we didn't so we're trying to keep some sense like we kept the original."

A sequel to the original 1996 film has been talked about since 2008, although McGregor voiced initial concerns.

The actor fell out with the director over casting Leonardo DiCaprio in The Beach, but they have since reconciled and he has said that he is "totally up" for the Trainspotting sequel.

Boyle's latest film Steve Jobs is released in U.S. cinemas on October 23, and in the UK on November 13.