Microsoft has confirmed that a pirated copy of Halo 2 for Xbox in the PAL video format and French language has started circulating on the Internet late Wednesday night over newsgroups and piracy sites.

Purportedly leaked from a European manufacturing plant used to press game discs, the company threatens severe action against those making the game available for download.

"We consider downloading this code, or making it available for others to download, as theft," said the company in a statement. "We are currently investigating the source of this leak with the appropriate authorities. Microsoft takes the integrity of its intellectual property extremely seriously, and we are aggressively pursuing the source of this illegal act."

As one of the most successful franchises on the Xbox, the leak of Halo 2 on the net presents serious concerns for Microsoft, who expects a high volume of sales when the game launches on November 9. Despite the leak, the company does not have any intention to push back the release date.

The theft mirrors the drama that happened to Half-Life 2 a year ago, with hackers stealing chunks of the PC shooter's source code and distributing it onto the net.

However, the theft will have less of an impact than Half-Life 2's, as the leaked Halo 2 will only be able to run on modified Xbox consoles, and is a whopping 3GB download. Microsoft has urged anyone with information on the source of the piracy to contact the company's antipiracy division at piracy@microsoft.com.