HP has called for changes to the Blu-ray format, insisting that it will back the alternative HD-DVD if its demands are not met.

The move represents yet another twist in the growing war between the two new DVD formats vying for dominance in advance of hardware launches.

"We are still supporting Blu-ray but we are very serious that we want these [new] technologies. If in the end, they are supported in one and not the other, we will have to make a choice," said Maureen Weber, general manager for personal storage at HP's Personal Systems group.

HP has asked the makers of Blu-ray to include two technologies in the specifications, both of which are now supported by HD-DVD.

One is known as 'mandatory managed copy', which allows users to copy high-definition movies onto PCs from discs and distribute them on home networks.

The second technology is iHD, which provides for new interactive features and is slated to be implemented in Microsoft's Windows Vista operating system.

HP explained that it is making the requests so that customers are not forced to choose between competing formats for DVDs.

The call follows yesterday's statement by Bill Gates that Blu-ray is " anti-consumer" and not good for PC users.

Analyst firm Forrester Research has declared Blu-ray as the winner in the battle between the two formats.

Sony and Toshiba held high-level talks earlier this year to try to unify the formats, but failed to resolve the matter.