By Robert Kozak

OTTAWA, March 9 (Reuter) Canadian vessels chased down and fired on a Spanish fishing boat in international waters off Canada's east coast on Thursday before seizing control of the ship in a bitter dispute over fish stocks.

Canada justified the actions outside its legal territorial limits, saying it was trying to conserve threatened stocks of one of the last commercial species in the region.

"Canada must act to save that resource," Fisheries Minister Brian Tobin sad.

"The government of Canada is today enforcing against the European Union, specifically Spanish vessels, a 60 day moratorium for fishing for Greenland halibut," Tobin said.

The Spanish vessel was being towed to a Canadian port where charges will be laid, Tobin said.

Thursday night, Canada called in envoys from the 15 member countries of the EU in an effort to solve the dispute diplomatically.

Deputy Foreign Minister Gordon Smith met the 15 ambassadors for 90 minutes and expressed regret over the dispute that led to the seizure of the Spanish vessel.

A spokesman for Smith said he "emphasized that Canada continued to want discussions to realise a political solution to the problem.

However, he "emphasized that Canada took this most gravely from a conservation point of view and urged the European Union ambassadors to get their countries to cease fishing so that Tobin's offer to talk during the 60 day moratorium period to resolve the problems could be implemented."

In Madrid, Spain said it had dispatched a naval ship to the North Atlantic to back its beleaguered fishermen.

The escalating war on the high seas between the European Union and Canada over the dwindling fish stocks comes after intense high level political negotiations failed. The European Union called the seizure a "flagrant violation of the law of the sea."

"The EU will find it difficult to stand still while there is direct action against one of its vessels," said the European Union's ambassador to Canada, John Beck.

"I cannot see that we can accept a forced moratorium in international waters dictated by one party," Beck told reporters in Ottawa.

The dispute flared after the EU rejected its share of a 27,000 tonne 1995 quota for Greenland halibut fixed by the Northwest Atlantic Fisheries Organisation (NAFO) and instead set itself a much higher limit.

Tobin said Canadian authorities chased down the Spanish vessel, the Estai, and took control of it after firing four bursts of warning shots across its bow.

"A (government) armed boarding crew ... boarded the Estai, secured the vessel and crew, and arrested the master of the Estai," Tobin said. "The vessel has now been fully secured and is fully under control of Canadian authorities.

Tobin vowed to continue seizing any vessels from the European Union that are fishing for Greenland halibut, also known as turbot, near Canada's 200 mile limit (322 km).

The turbot may be the last viable commercial fish stock in the North Atlantic. The once viable northern cod has all but been destroyed by overfishing, throwing thousands of Canadian fishermen out of work.

The 60 day moratorium will apply to halibut both inside and outside of Canadians waters in the area known as the Grand Banks off the coast of Newfoundland, he said.

Earlier on Thursday in Brussels, the European Union's executive commission accused Canada of piracy.