BRUSSELS (Reuters) - Part of a law to promote green energy violates the treaties underpinning the European Union, an adviser to the highest EU court found on Tuesday, stoking political debate about subsidies for renewable power.
The opinion will be considered further by the Court of Justice of the European Union over the next three to six months and could lead to the invalidation of an article of the EU law.
The European Commission - the EU executive - said it could not comment on ongoing cases.
An advocate general, who advises the European court in Luxembourg, found Sweden had respected EU law on promoting renewable energy, but in doing so had broken rules enshrined in the EU treaties on free movement of goods.
Opinions from advocates general are respected by the court in a majority of cases.
If the court confirms there is a conflict, the relevant section of the EU law would become invalid in two years' time, giving the Commission and member states two years to come up with an alternative.
"Article 3, paragraph 3 of the directive 2009/28 is invalid in that it gives member states the power to prohibit or restrict access to their support regimes for (energy) producers whose renewable energy installations are situated in another member state," Advocate General Yves Bot said in his opinion.
Sweden refused to award subsidies it hands out for domestic renewable energy to wind power generated on the Aland archipelago, part way between Finland and Sweden.
Although it is part of Finland, Aland has its own parliament and is Swedish-speaking. Similarly, its link to the European Union is regulated by a special protocol.
Wind energy company Alands Vindkraft went to the Swedish courts, arguing Sweden was giving an unfair advantage to Swedish-produced energy. At the end of 2012, the Swedish courts referred the matter to the EU court.
The case has political resonance as Europe struggles to wean itself off expensive green energy subsidies blamed for inflating costs and making the European Union less competitive.
The Commission is pushing for harmonized subsidy regimes across the EU and seeking to support cross-border movement as part of a single energy market to contain costs and maximize available resources.
(Reporting by Barbara Lewis; Editing by Dale Hudson)