THE Spanish ambassador has been summoned to the Foreign Office over the activities of a Spanish naval vessel operating in waters off Gibraltar.

Europe Minister David Lidington said he was "extremely concerned" by the Spanish ship which he said had sought to redirect two other vessels heading to and from the Port of Gibraltar claiming they were in Spanish territorial waters.

"The vessels were in international waters off Gibraltar, and the actions of the Spanish Navy vessel constitute a breach of the UN Convention on the Law of the Sea," he said.

"Freedom of navigation in international waters is a vital principle of international law. This represents a cynical attempt by the Spanish government to disrupt Gibraltar's economy."