Warner Bros. is probing the leak of more than half an hour of “Harry Potter and the Deathly Hallows: Part 1” on Internet file-sharing sites this week.

A Warner spokesman said Wednesday that the studio had not determined the source of the pirated footage; no screeners of the “Potter” pic have been created.

“This constitutes a serious breach of copyright violation and theft of Warner Bros. property,” the studio said in a statement Wednesday. “We are vigorously investigating this matter and will prosecute those involved to the full extent of the law.”

The first 36 minutes of the seventh Potter pic became available for download on several file-sharing sites such as BitTorrent.

It’s the first time that pirated footage from a major studio film has been on the Web prior to release since last year’s posting of Fox’s “X-Men Origins: Wolverine.”

“Harry Potter and the Deathly Hallows: Part 1” began its worldwide launch on Wednesday with openings in several major European markets — Austria, Belgium, Germany, Holland and Sweden — along with Egypt and Turkey. Australia and Russia are the major markets set to launch today, and most markets, including the U.S. and the U.K., open Friday.

The Fandango movie ticketing site reported Wednesday that “Deathly Hallows” has sold out more than 2,200 of its showtimes in advance, representing 96% of all daily ticket sales. It also said its survey of more than 1,000 ticket buyers showed 94% indicating that the darker elements increased their interest in seeing the movie.

The final “Harry Potter” movie will be released July 15.