BRUSSELS, July 5 (Reuter) - The European Commission may take Norway to court for allegedly violating a free trade deal by preventing European Union fishermen from unloading their catches in Norwegian ports, a Commission spokesman said on Wednesday.

The Commission believes Norway is breaking the European Economic Area (EEA) agreement by its actions against Danish fishing boats catching spring-spawning herring in international waters off Norway, spokesman Marco Zatterin said.

He said the Commission was "considering action" and that it may decide to take the case to the Luxembourg-based European Court of Justice.

A Norwegian official said Norway, fearing the consequences of unregulated fishing, interpreted the EEA agreement differently. The country took action to protect the stocks of a fish species which had recovered after virtually disappearing a few decades ago.

Norway wants the EU to stop the fishing until "appropriate" regulatory measures have been implemented to ensure a sustainable harvest, he said.

The issue would be on the agenda of the next meeting on July 18 of the EEA joint committee of the EU and the European Free Trade Association, of which Norway is a member, Zatterin said.

The 18-nation EEA, which came into being in early 1994, expands the internal market of the 15-nation EU to include EFTA-members Norway, Iceland and Liechtenstein.

Until a few years ago the spring-spawning herring was only available in Norwegian waters. But then it started to migrate, making it available to fishermen from Denmark, the Netherlands and Britain.

Zatterin said Norway had become worried about the protection of the fish stocks and had asked the EU to fix a quota.

The EU was willing to do this but in a multilateral framework through the North-East Atlantic Fisheries Commission (NEAFC) and not bilaterally, he said.

The Commission had proposed an extraordinary meeting of NEAFC but the Norwegians did not want to convene such a meeting, prompting Fisheries Commissioner Emma Bonino to express her disappointment earlier this week.

She stressed that since it was a regional problem it needed a regional solution, Zatterin added.

But the Norwegian official, who did not want to be named, said Norway did not object to the matter being handled by NEAFC but that it wanted this to be done at the regular meeting in the autumn.

Zatterin also said there did not seem to be a serious problem with the stocks, but the Norwegian official said this was because Norway and countries such as Russia had shown restraint in fishing the species for a quarter of a century.