FBI agents are investigating how a full-length version of X-Men Origins: Wolverine, one of spring's most anticipated Hollywood blockbusters, was leaked online this week.

Movie giant 20th Century Fox issued a statement about the incident on Wednesday, noting that the leaked copy was a "stolen, incomplete and early version" of the superhero movie "without many effects, had missing and unedited scenes and temporary sound and music."

Officials from both the Motion Picture Association of America and the Federal Bureau of Investigation have been assigned to the case, Fox added.

"We forensically mark our content so we can identify sources that make it available or download it. The source of the initial leak and any subsequent postings will be prosecuted to the fullest extent of the law," according to the statement.

Though the studio said the leaked online copy had been removed, it's estimated that the film was shared thousands of times before being taken down.

Internet users who saw the leaked footage confirmed on various websites that visual effects were indeed incomplete. Many commented that, because of this, hardcore fans would likely still rather wait to see the finished product in theatres.

"We are encouraged by the support of fan sites condemning piracy and this illegal posting and pointing out that such theft undermines the enormous efforts of the filmmakers and actors and, above all, hurts fans of the film," Fox said.

In X-Men Origins: Wolverine, actor Hugh Jackman reprises his role as the titular mutant from the X-Men movie franchise. The film, set to hit North American theatres on May 1, explores the origin story of the beloved comic book hero.