LOS ANGELES — "X-Men Origins: Wolverine" isn't due in theaters until next month, but the prequel has already hacked its way online.

A high-quality, full-length work print of the 20th Century Fox film appeared online Tuesday evening. The studio said it had the file removed, but copies quickly propagated and continue to appear on several file-sharing Web sites.

• CTV.ca Trailers: X-Men Origins: Wolverine

The movie focuses on the beginnings of Hugh Jackman's clawed Marvel superhero Wolverine and is set for a May 1 release.

Fox vowed in a statement Wednesday that the source of the "stolen, incomplete and early version" of the movie would be prosecuted and said the FBI and MPAA are investigating. The studio also insisted that the version of the film posted online was "was without many effects, had missing and unedited scenes and temporary sound and music."