Simon Kinberg has refused to rule out the possibility of recastings for 'X-Men: Apocalypse'.

According to the writer-producer, 20th Century Fox has been contemplating whether to cast new actors in the iconic roles from the 'X-Men' franchise.

He told Yahoo: ''It'd be very hard to do, because Halle [Berry], Famke [Janssen], and Jimmy [Marsden] and others have done such wonderful jobs of bringing those characters to life.

''But I also would have said before 'First Class' that there would be no actors who can stand alongside Ian McKellen and Patrick Stewart.''

The roles of Professor Xavier and Magneto were played by McKellen, 75, and Stewart, 74, in Fox's first three films, and more recently by James McAvoy, 35, and Michael Fassbender, 37, respectively.

And looking to the future of the franchise, Kinberg said: ''In Apocalypse, it will really be the continuation of the 'past' of Days of Future Past.''

Earlier this week, it was confirmed that Bryan Singer will direct 'X-Men: Apocalypse'.

Singer, 49, has worked on three previous instalments of the Marvel franchise and will return as the director of the next movie.

'X-Men: Apocalypse' is set to hit cinema screens on May 27, 2016.