Ryan Reynolds will play Deadpool and will.i.am will star as Wraith

Reynolds, currently in romantic comedy Definitely, Maybe, will play Deadpool - an assassin with healing abilities.

Meanwhile, will.i.am is expected to play John Wraith, a mutant who has the power to teleport and ages very slowly.

The film, which sees Hugh Jackman reprise his role as Wolverine, is due for release in May 2009.

Taylor Kitsch, from hit US football drama Friday Night Lights, has also signed on to appear as the famous card-throwing character, Gambit.

Scream star Liev Schreiber has already joined the cast as Victor Creed, also known as Sabretooth.

The film, set 17 years before the X-Men movies, reveals the origins of the Wolverine character and introduces other mutants not yet seen in the franchise of films.