The encryption on high-definition DVDs has been bypassed, the consortium backing the copy protection system on discs has confirmed.
The high-definition DVD format war is raging
At the end of last year a hacker claimed he had defeated the protection on a number of HD-DVD titles, leading to fears the entire system was broken.
But the Advanced Access Content System (AACS) Licensing Authority has said the breach is limited.
"It does not represent an attack on the AACS system itself," the group said.
The AACS group has admitted that a hacker had managed to decrypt some discs and other people were now able to make copies of certain titles.
The hacker, known as muslix64, has been able to access the encryption keys which pass between certain discs and the player. Once those keys have been obtained the disc can be stripped of its encryption enabling the digital content to be played on any machine.
A spokesman for the AACS group said the large size of the files and the high cost of writable hi-def discs made widespread copying of the movies impractical.
The attacks on the new format echo the early days of illegal trafficking in music files, AACS spokesman Michael Ayers said.
AACS copy protection is used on both HD-DVD and Blu-ray titles, giving rise to concern from the entire movie industry about the security of its content.
A large-scale breach of AACS could be a threat to the $24bn DVD industry and dent hopes that high-definition discs would invigorate the market.
There are fears that piracy could harm the industry
The hacker obtained the keys from "one or more" pieces of software which plays high-definition DVDs, said Mr Ayers.
But the AACS group would not identify them or say whether their AACS licensing would be revoked.
"We certainly have not ruled out any particular response and we will take whatever action is appropriate," Mr Ayers said.
In a recent interview with digital media website Slyck, hacker muslix64, said his motivation for defeating the protection system was frustration.
"I'm just an upset customer. My efforts can be called 'fair use enforcement'," he said.
He said he had grown angry when a HD-DVD movie he had bought would not play on his monitor because it did not have the compliant connector demanded by the movie industry.
As part of the copy protection system on high-definition DVD, content providers can insist that movies will only play correctly if there are HDMI - or in some specific cases, compliant DVI - ports on the player and screen as these two connectors can handle the HDCP copy protection system.
"Not being able to play a movie that I have paid for, because some executive in Hollywood decided I cannot, made me mad," said the hacker.