Major film and television studios have lost a landmark case over illegal video downloads in Australia.

The High Court upheld a previous ruling that internet service provider (ISP) iiNet did not authorise copyright infringement among its customers.

US and Australian studios had wanted iiNet to stop its customers from downloading pirated material.

In 2010, a federal court had ruled in favour of iiNet, saying it did not authorise the downloads.

The court also said that the country's third-largest internet provider did not have the technical ability to prevent the piracy.

The unanimous ruling from the High Court upheld the lower court's decision.

"The High Court held that the respondent, an internet service provider (ISP), had not authorised the infringement by its customers of the appellants' copyright in commercially released films and television programmes," the court stated.

"Rather, the extent of iiNet's power to prevent its customers from infringing... copyright was limited to an indirect power to terminate its contractual relationship with its customers."

The 2010 judgment was the first time a court had ruled on whether an ISP could be held responsible for copyright violations by its users.

The case revolved around thousands of downloads over Perth-based iiNet's network in 2008 using a file-sharing programme.

The Australian Federation Against Copyright Theft group, made up of 34 film, TV and music companies, had appealed the lower court decision, saying it set a dangerous precedent.

The group's managing director, Neil Gane, was quoted by news agency Agence-France Presse as saying that the ruling exposed the failure of copyright law to keep pace with the online environment.

"Both judgements in this case recognise that copyright law is no longer equipped to deal with the rate of technological change we have seen since the law of authorisation was last tested," he said.