Warner Bros. Entertainment said Thursday that its home video division will release DVDs in the high-definition Blu-ray format. The move further tips the scales in an industry weighing the merits of two rival next-generation technologies.

Warner, which had decided to distribute films in the popular HD DVD format, is now the second big Hollywood company to say it will also release films in Blu-ray. However, the trend toward supporting two formats seems to be one-directional; companies dedicated to Blu-ray have not moved to add HD DVD to their mixes.

The competing formats are each backed by powerful technology companies, including Sony for Blu-ray and Toshiba for HD DVD, leading analysts and executives to fear a format war similar to the one between VHS and Betamax more than two decades ago.

For several months, Hollywood studios have been split almost evenly between the two formats, each studio saying it would release high-definition DVDs next year only in one format or the other. Paramount Pictures, however, broke ranks earlier this month to say it would release films in both. Warner's decision accelerates that trend.

On Wednesday, however, computer giant Hewlett-Packard appealed to the Blu-ray group to include some HD DVD features, including a so-called mandatory managed-copy function that previously had been a key concern of Microsoft and Intel, which support HD DVD.

"Managed copying" would let consumers use a home computer or server to copy a DVD so they could then stream or play the DVD on a home network, but not to burn the DVD again or send its contents online. HD DVD specifications require the managed-copying feature, but Blu-ray makes it optional.

Warner said it will join the Blu-ray Disc Association's board of directors but still plans to release movies in HD DVD format as well. Discs and players of both types are expected to reach shelves next year.