Consumer Ombudsman Bjoern Erik Thon told Reuters he hoped other countries would follow the Norwegian example and file their own cases against the U.S. computer giant.

Thon said on Tuesday that iTunes -- Apple's online store for music downloads -- had not met its demands to change its digital rights management (DRM) system to make its music available for all music players.

"I want them to make their services interoperable so that you can play music bought on iTunes on other devices, including mobile phones," Thon told Reuters in a telephone interview.

Apple's attorney in Norway declined to comment, and Apple officials did not respond to repeated phone messages and emails.

"The consumer's freedom of choice in the online music market is an important right," he said in a statement on Monday.

A dialogue with iTunes over the past two years had led to some improvements in contract terms for downloading music, but on the main issue of availability of iTunes music on devices other than iPod "there has not been much movement," Thon said.

Thon's office, which is an independent government agency, has worked together with consumer protection bodies in Scandinavia, Germany and France to put pressure on iTunes.

"Next we will try to gather a number of countries to support this case, although this case will be brought in front of the Norwegian Market Council and handled according to Norwegian law," Thon said.

The council serves as a court for consumer complaints.

"It is important to show that we have a broad alliance of consumer bodies backing us, and if we win this case, I hope they will follow in our footsteps and take action," he said.

The consumer ombudsman said that consumers must be able to choose which music device they wish to use to listen to music bought from iTunes.

"It's a consumer's right to transfer and play digital content bought and downloaded from the Internet to the music device he himself chooses to use," Thon said and added: "iTunes makes this impossible or at least difficult, and hence, they act in breach of Norwegian law."

iTunes has until November 3 to respond, before the case goes to the Market Council, the ombudsman said.