[MADRID] Spain proposed on Friday sharing sovereignty over Gibraltar after Britain voted to leave the European Union, saying this could be a prelude to bringing the overseas territory back under its control.
The comments by acting foreign minister Jose Manuel Garcia-Margallo are likely to spark concern in the tiny rocky outcrop on Spain's southern tip, which has long been the subject of an acrimonious sovereignty row between London and Madrid.
"Our formula... is British-Spanish co-sovereignty for a determined period of time, which after that time has elapsed, will head towards the restitution of Gibraltar to Spanish sovereignty," Mr Margallo told Spanish radio.
Spain wants Gibraltar back under its control centuries after it was ceded to Britain in 1713.
The country's conservative government, which has been in place since 2011 and is expected to win elections Sunday - albeit without an absolute majority - has been particularly vocal about its desire to see Gibraltar come back into its fold.
The Rock is now worried that it will be at the mercy of Madrid without the protection of the EU, which has had to intervene in the past to ease rows between the two.
Mr Margallo said the issue of Gibraltar was no longer within the remit of the European Union, after Britons voted to leave the bloc in Thursday's referendum.
"It is now a bilateral issue that will be negotiated exclusively between the United Kingdom and Spain," he said, adding a solution would have to be found if Gibraltar wanted to keep its access to the EU's single market.
The Rock relies in large part on access to the single market for its thriving economy.
In a tweet, Gibraltar's chief minister Fabian Picardo called for calm.
"We have surpassed greater challenges. It is time for unity, for calm & for rational thinking. Together & united we will continue to prosper," he said.
Gibraltarians turned out en masse to vote in the referendum Thursday, and 96 per cent of those who cast their ballot voted to remain in the European Union.
But they were not the only ones to wake up in shock to the result.
Spanish workers on the other side of the border, many of whom depend on jobs in Gibraltar for their livelihood, reacted with "a lot of concern and fear." The border town of La Linea de la Concepcion is of particular concern.
Unemployment in this 72,000-strong city stands at 40 per cent, one of the worst-hit places in Spain, and the majority of those who work do so over the border.
Juan Jose Uceda of the Association of Spanish Workers in Gibraltar said the grouping feared that the "work situation for thousands of Spaniards and foreigners working in Gibraltar will become more difficult."
They fear that the crucial land border crossing to Gibraltar - a long-time flashpoint in the row between the Rock and Spain - could be affected as it has been in the past.
In one particularly belligerent row over disputed waters, Spanish authorities upped border checks in 2013, creating hours-long logjams and forcing the European Commission to wade in and ease the crisis.
But Spain's acting Prime Minister Mariano Rajoy sought to ease their concerns in a televised address.
"With regards to Spanish citizens working in Gibraltar... their rights have not changed," he said.