'The Hangover III' will be filmed in Las Vegas.

While the second instalment in the comedy franchise - starring Bradley Cooper, Ed Helms and Zach Galifianakis - was set in Asia, the third and final movie will return to its Roots in the gambling capital in the state of Nevada.

According to the Las Vegas Sun, parts of the film featuring guest star Mike Tyson will be shot just off the Las Vegas Strip and at Caesars Palace.

The movie is set to feature the friends trying to spring Alan (Zach) from a mental hospital and will also be shot in Tijuana and Los Angeles with production expected to begin in September.

Director Todd Phillips is back on board for the project and promised the customary ''Mayhem, despair and bad decisions''.

He said: ''I'm so excited to embark on another 'Hangover' film with Bradley, Ed and Zach. We're going to surprise a lot of people with the final chapter we have planned.

''It will be a fitting conclusion to our three-part opera of mayhem, despair and bad decisions.''

Speaking about the project previously, 'Limitless' hunk Bradley claimed it would be unlikely to ''adhere to the structure'' of the previous two movies.

He said: ''We adhered to the formula in the second one, for those of you who've seen it, and the third one, which would close the whole, sort of, trilogy, which now it would be a trilogy - even though we thought we would never make a second one, let alone anybody see the first one.

''I think it will maybe not adhere to the structure. It might be different.''