Blu-ray Disc adoption took a leap forward today following video and games rental chain Blockbuster's decision to roll out the format to 1,700 of its US stores from July.

The rental firm's decision to stock the HD DVD rival is based on "growing demand for high definition DVDs", it said, adding that rental figures of Blu-ray Discs are already outpacing those of HD DVDs in the 250 of its US stores that currently offer the formats.

Although Blockbuster will still continue to stock HD DVDs both online and in said 250 stores – which it has done since November 2006 – it seemed keen to resist asserting the bold claim that Blu-ray will win the 'VHS vs Betamax'-style fight of the mid 1970s.

"While it is still too early to say which high-definition format will become the industry standard, we will continue to closely monitor customer rental patterns both at our stores and online," Matthew Smith, Blockbuster's head of merchandising, said in a statement.

The announcement has already prompted a scathing response from the North American HD DVD Promotional Group, which branded Blockbuster’s decision as “short-sighted” and based mainly on Blu-ray sales of budget-busting films like Spider-Man.

"I think trying to make a format decision using such a short time period is really not measuring what the consumer is saying," said Ken Graffeo, co-president of the group.

Blu-Ray has a strong gamut of video-business backers, including Sony, MGM, Fox and Warner. HD DVD is backed principally by Universal and Paramount, but Warner also offers HD DVD product.

HD DVD's principal hardware backer is Toshiba, which last week slashed its forecast for HD DVD player sales.