The European Commission said Tuesday it has asked several Hollywood studios to explain why they have chosen either the Blu-ray Disc or HD DVD format for movie discs to see if they are breaking EU rules that bar companies from shutting out rivals.

The Sony Corp. (SNE)-backed Blu-ray format has won strong support from Hollywood. The Walt Disney Co. (DIS), News Corp.'s (NWS) 20th Century Fox and Sony Pictures have released Blu-ray discs but not the competing HD DVDs, developed by a consortium led by Toshiba Corp.

General Electric Co.'s (GE) Universal Studios releases high-definition movies exclusively on HD DVD — the only major studio to do so.

• Click here for FOXNews.com's Personal Technology Center.

EU spokesman Jonathan Todd stressed that regulators were merely looking for information on how studios choose the technology format for their film releases and have not accused the companies of violating antitrust law.

"We are currently fact-finding and have sent requests for information to a number of Hollywood studios," he said, refusing to name the companies. "It is not a formal investigation."

Todd said the EU was acting on its own initiative and had not received complaints to trigger the probe. The EU's executive arm has asked for replies by July 6.

The studios' stalemate means movie lovers seeking many hit films have to opt for either Blu-ray or HD DVD. Only Time Warner Inc.'s (TWX) Warner Bros. and Viacom Inc.'s (VIA) Paramount Pictures are releasing movies in both formats.

All but the most adventurous consumers have stayed away from choosing sides in the battle for fear of being stuck with the losing technology, much the same as happened when VHS and Betamax battled it out for videotape dominance in the 1980s.

The issue is not just academic: Blue-ray and HD DVD discs require their own players and don't work with current DVD players.