Sales of high-definition DVD players appear to have swung in favor of Blu-ray Disc after the announcement by the Warner Brothers film and television studio that it would stop releasing discs in the rival HD DVD format.

In the week after Warner's Jan. 4 announcement, sales of Blu-ray devices accounted for 90 per cent of all high-definition hardware sales in the U.S., according to NPD Group, a market research company.

Throughout 2007, sales of high-definition players were split roughly 50-50 between Blu-ray and HD DVD, as the big film studios lined up behind the two formats.

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NPD Group stressed that the figures only related to one week's sales and that not too much should be read into them, but analysts said that the swing in sales could not be attributed solely to seasonal offers and fluctuations in the price of devices because of Christmas.

Toshiba, the main manufacturer of HD DVD players, dismissed suggestions that the figures were indicative of a wider change, saying they were likely the result of Blu-ray players having been given away to buyers of some flat-screen TVs.

It nonetheless responded by cutting the price of its entry-level machines from $299 to $149.99. A comparable Blu-ray device costs about $300.

With Warner's departure, only DreamWorks, Paramount and Universal still support HD DVD. Walt Disney, Twentieth Century-Fox and MGM have all already said that they are backing Blu-ray. Sony's own Columbia Pictures naturally supports Blu-ray.

Andy Parsons, head of the Blu-ray Disc Association, was quoted in The New York Times as saying: "Consumers have gotten the message loud and clear. Lowering prices sends the message that Toshiba is having a fire sale."

Toshiba has said that it will ramp up its marketing campaign for HD DVD, including running ads during the Super Bowl.