A US Department of Justice (DoJ) official has criticised European anti-trust activities over proprietary digital music technology.

Thomas Barnett, assistant attorney general at the DoJ's anti-trust division, warned that forcing companies to reveal their intellectual property stifles innovation. He used Apple as an example, in a nod to growing discontent in Europe, regarding the way that music purchased from iTunes is tied to the iPod.

But the architects of complaints against Apple in Europe say he's got it wrong. "We're not attacking intellectual property rights but saying they should be implemented in a way which doesn't dictate which player you use," said Torgeir Waterhouse, a senior advisor with the Norwegian Consumer Council.

His organisation filed a complaint with Norway's consumer representative arguing that it is illegal for Apple to limit iTunes customers to playing music from the store exclusively on iPods.

Along with similar representatives in Denmark and Sweden, the Norwegian ombudsman asked Apple to defend its policy. In a written reply, Apple said it won't budge on the issue but the company plans to meet representatives from the countries later this month to further discuss the issue. If Apple won't open up, the ombudsman will take the company to court.

Waterhouse suggests that Apple could solve the problem by licensing its digital rights management technology to other device makers so that iTunes customers could choose among devices or opt for an open standard that would be compatible with more devices.

Barnett's criticisms of European anti-trust policy, including comments that the policy is aimed at helping competitors instead of consumers, are generally in line with comments from US officials since the Bush administration came to power, said Scott Megregian, a partner and head of the European competition group in the law firm McDermott Will & Emery.

He disagrees with the argument that requiring companies to open up some of their technology stifles innovation. "That's an argument without support," he said. "Microsoft hasn't stopped innovating that I can tell, despite regulations and attack by the EU."

So far, the European Commission has likely communicated with the countries that are pursuing Apple and has probably expressed an opinion on the matter, he said. While no official complaints have been filed with the Commission, if one is, the result will have the makings of a historical battle. "This has the potential to be the next big high-profile dispute," Megregian said.