Foreign Minister Alfonso Dastis added that the discussion about the British territory on Spain’s southern coast would be bilateral between the two countries, according to news agency Efe.

“I think no: this does not depend only on us, it depends on the United Kingdom and above all on an agreement being reached,” Dastis told a press conference, answering a question as to whether Spain would veto a general agreement between the EU and UK, for which negotiations began on Monday, because of Gibraltar.

EU leaders have granted Madrid a veto over any future deal with Britain that would involve the territory. The EU 27 guidelines state that “no agreement” after Brexit between the EU and Britain could apply to Gibraltar without a bilateral agreement between Madrid and London.

Britain has expressed alarm over the clause and British Prime Minister Theresa May has insisted she will “never” allow Gibraltar to slip from British control.

With a population of just over 32,000, Gibraltar has been a British overseas territory since 1713 but Spain has long laid claim to it. Some 10,000 people cross from Spain to Gibraltar to work every day.

Authorities in Gibraltar fear Spain is trying to take advantage of Brexit to impose its control over the territory.

Gibraltarians voted overwhelmingly to remain in the EU in last June's Brexit referendum, but they still appear set on remaining British after the vote.

Dastis further confirmed that “what is fundamental, and what we expect the United Kingdom to understand, is that there is a structural relationship between the United Kingdom and the Europe Union.”

“The question of Gibraltar does not have any reason to be the first or most important thing in the framework of this discussion,” he said, adding that it will be necessary to first “clarify this framework” regarding future relations and later “we will see how this applies to Gibraltar”.

“Yes, it will be a bilateral discussion, but not immediately and it will not be one of the urgent issues.”

When asked whether the EU’s chief Brexit negotiator, Michael Barnier, will be authorized to address the topic of Gibraltar with his British counterparts, Dastis said “it is not a matter of authorization”.

“The guidelines say what they say, and we are not going to put in a strict and rigorous plan, and verify the instructions day to day.”