German and French consumer groups have backed a Scandinavian campaign to force Apple Inc. to make its iTunes online store compatible with digital music players that compete with its iPod.

Songs bought and downloaded on iTunes work with iPods players but not rival models. Nor can iPods usually play copy-protected music sold through non-Apple stores.

However, the system was challenged in June 2006 by Swedish, Danish and Norwegian consumer agencies, who argued that Apple was breaking their contract and copyright laws. Billboard understands that Nordic regulators have met Apple officials at least twice over the complaints by Scandinavian agencies.

The campaign has now been joined by French consumer lobby UFC-Que Choisir and Germany's Federation of German Consumer Organizations (VZBV).

"Interoperability and more flexibility in using downloaded content is key for the further development of the legal music download market", says Patrick von Braunm?hl, Deputy Director of VZBV.

In a joint statement, the consumer groups from the five countries claimed that customers had the right to play material purchased online on a portable device of their own choice. "Contract clauses that make this impossible or too inconvenient are unfair and should be revoked," the statement said. The groups suggest this might be solved by renegotiating with record companies so that the music can be sold without DRM.

Apple did not comment on the latest developments.

A French law that allows regulators to force Apple to make its iPod player and iTunes store compatible with rival offerings went into effect in August.