The possibility of Britain leaving the European Union is raising serious questions about what might happen to Gibraltar, the tiny British Overseas Territory that borders Spain.

In an interview with Radio Nacional de España on Friday, Spain’s acting Foreign Minister José Manuel García-Margallo said that if Britain were to leave the EU “we would be talking about Gibraltar the very next day”.

Gibraltar reacted angrily to the remark. 

“The declared intent of the Caretaker Foreign Minister of Spain to bring the question of Gibraltar to the fore in the event of the UK and Gibraltar leaving the EU confirms the analysis that has already been made,” the Government of Gibraltar said in a statement to The Local.

“It is safer and more secure for Gibraltar to remain in the EU in order to deny Mr Margallo the opportunity to pounce on us,” the statement continued.

“This is exactly the type of attitude that we have come to expect from Sr. Margallo and it no doubt pervades so many others of his mindset,” Gibraltar’s Chief Minister Fabien Picardo told The Local in a statement.

“It usefully sets out the danger that those who choose Brexit potentially create for Gibraltar if there is also a Partido Popular government in Spain in the future.”

Speaking in the run-up to Gibraltar’s elections in November, which he won, Picardo said his centrist alliance was firmly of the view that Britain should remain in the EU and that access to the single market and freedom of movement were vital for Gibraltar.

“We have fought to ensure that Gibraltar is able to vote in the Brexit referendum so that we can influence that decision,” Picardo said.   

“Our primary challenge as a people after the election is, therefore, to work to keep the UK in the EU.”

Picardo has had several clashes with Spain, which has a centuries-old claim over Gibraltar's sovereignty and until recently imposed sanctions and restrictions.

Picardo and Spain's ruling conservative Popular Party (PP) have argued over the smuggling of cheap cigarettes from Gibraltar into Spain and the territory's low-tax regime.

There has also been tension over fishing rights and law enforcement in the waters around the Rock, which are claimed by both Britain and Spain.

Picardo has at times taken an assertive stance toward Spain, but insists this was proportional to the PP's approach to Gibraltar.

“Dealing with Garcia-Margallo has required us to be tough on occasions,” he said.

“I make no apology for that.”