Halle Berry returns in the futuristic fantasy X-Men 2

X-Men 2 is opening at a record number of cinemas across the US on Friday, kicking off the summer blockbuster season.

X2: X-Men United will be released in 3,741 cinemas to ensure maximum ticket sales before its biggest rival, Matrix Reloaded, is released on 15 May.

It opened in the UK on Thursday, and is opening in 93 countries this week - making it the largest simultaneous worldwide release.

X-Men 2 picks up where its predecessor left off, following the battles between rival mutant gangs who have taken over Earth.

Movie executive Bruce Snyder, of producers 20th Century Fox, said the next fortnight was crucial to the sequel's success.

"Matrix Reloaded is coming in two weeks, and we wanted to get in there before Matrix did - because we won't be able to get in there later," he said.

"Then we'll clear out by the time Matrix comes to town."

Both films are hoping to emulate the box office fortunes of their forerunners.

The first X-Men made $54.5m (�34m) on its debut in 2000 but the sequel is expected to top that, with estimates of around $70m (�44m) being mooted.

But it is not predicted to outdo another Marvel creation, Spider-Man, which grossed a record-breaking $114m (�71m) last year.

The original cast have returned for X-Men 2, including Hugh Jackman, Halle Berry, Patrick Stewart, Sir Ian McKellen and Anna Paquin.

Other summer blockbuster sequels due out this summer include Terminator 3 and Tomb Raider 2.