The Spanish town of La Linea de la Concepción next to Gibraltar. | Jon Nazca / Reuters

Spain will seek co-sovereignty on Gibraltar following Britain's vote to leave the European Union, acting foreign minister Jose Manuel Garcia-Margallo said today, adding that the vote completely changed the outlook on the future of the island.

The small island off the south coast of Spain, a British Overseas Territory since 1713 and known to its 30,000 residents as the Rock, is a major point of contention in Anglo-Spanish relations.

"It's a complete change of outlook that opens up new possibilities on Gibraltar not seen for a very long time. I hope the formula of co-sovereignty - to be clear, the Spanish flag on the Rock - is much closer than before," he said.

A spokesman for Gibraltar's government declined to comment on the Brexit vote and referred to previous statements made on how co-sovereignty had already been rejected by around 99 per cent of Gibraltarians in a previous local referendum.

Spain will push for Gibraltar to stay out of any general negotiations with the European Union following Britain's exit from the bloc and will aim for bilateral talks to seek co-sovereignty and eventually Spanish control of the island, Garcia-Margallo said.