The EU was entitled to cap roaming rates in 2007 as network operators pocketed huge profits but resisted less drastic ways to cut the sky-high costs of using mobile phones in Europe, the EU advocate general said Thursday.

The opinion by Advocate General Miguel Poiares Maduro now goes to the European Court of Justice, which often follows that advice.

The opinion is a setback for mobile phone operators Vodafone, Telefonica O2, T-Mobile and Orange. They had challenged the validity of the EU roaming law in a British court, which referred the case to the European court.

But it is boost for the European Commission, which cites the roaming law as an example of how the European Union works to help consumers from the Azores to Lapland.

Poiares Maduro said the EU was entitled to set maximum roaming rates for a three-year period to ensure uniform prices and conditions across the 27 EU nations.

He noted that if pricing been left to the bloc's 27 national regulators it would have taken a very long time for Europeans to see roaming rates decline. Poiares Maduro said the European Commission failed repeatedly to get network operators to lower their rates, which varied widely and earned them profits of up to 400 percent.