BRUSSELS (AP) — A top European Union judge says the ride-sharing service Uber is a transport company and could be required to obtain licenses and permits under national law in the 28 EU member states.

The case was brought to the European Court of Justice by a taxi company in Spain that claimed a Barcelona Uber branch was engaged in unfair competition.

Advocate General Maciej Szpunar said in a legal opinion Thursday that Uber there was providing a comprehensive system for on-demand urban transport that can be regulated.

This means it could not be considered an "information society service" that would benefit from EU principles on the freedom to provide services.

Such opinions are non-binding but are often endorsed by the ECJ. National courts have banned Uber services in other European cities.