By Belén Carreño and Robin Emmott
BRUSSELS (Reuters) - Spain will revive its bid for shared sovereignty over Gibraltar once Britain has left the European Union, the country's prime minister said on Sunday, adding Madrid had the support of the bloc to resolve the 300-year-old dispute.
Speaking after an EU leaders' summit, Sanchez said Spain's position over Gibraltar, a British territory since 1713, was stronger after the agreement of a Brexit deal on Sunday because Spanish policy effectively became EU policy.
"We are going to resolve a conflict that has been going for over 300 years," Pedro Sanchez told a news conference, adding he had said the same thing to British Prime Minister Theresa May, who met the EU's 27 leaders to endorse the withdrawal treaty that she will now put to the British parliament.
Asked if Spain would seek a discussion over joint sovereignty once Britain leaves the bloc on March 29, 2019, Sanchez said: "We will discuss all issues."
The small peninsula attached to Spain is a major point of contention in Anglo-Spanish relations. Spain has long claimed sovereignty.
Gibraltar residents rejected shared sovereignty with Spain in a referendum in 2002. "The Rock", as it is known by locals, is due to leave the EU along with the United Kingdom.
May told reporters on Sunday that "Gibraltar is British" and that when she negotiated for Britain, she did so for the territory, but declined to go into more details.
However, given that 96 percent of its population voted in Britain's 2016 referendum to remain in the EU, the mood was now different, Spanish officials said.
"This puts Spain in a position of strength in negotiations with the United Kingdom over Gibraltar that we have not had until now," Sanchez told reporters after the summit.
He was referring to a 1986 agreement when Spain joined the bloc and had to adapt its Gibraltar policy to British policy within the EU. He said that situation was now being reversed, a view also shared by many in the bloc, one EU official said.
Signalling such support, European Commission President Jean-Claude Juncker said many Europeans did not realise the importance of Gibraltar for Spain.
"We all lose (with Brexit), especially the United Kingdom, but regarding Gibraltar, Spain wins," said Sanchez, who made no attempt to hide his delight during the news conference.
Shared sovereignty in Gibraltar, home to 30,000 people, a British naval base and an airport partly contested by Spain, could echo similar arrangements in Europe such as Andorra and the Isle of Man, said Ignacio Molina, an analyst at the Elcano Royal Institute think-tank in Madrid.
"There could be a special postal service embedded into both Spanish Correos and Royal Mail, local number plates with the European flag, healthcare provision in Spain, possible Spanish police action in Gibraltar," he said.
"Of course, the airport would be shared, there would be no control of persons at the border," he added.
Gibraltar's airport dispute centres around sovereignty over a narrow strip of land connecting Gibraltar to Spain. Spain says the isthmus was not included in the treaty ceding Gibraltar to Britain and has always been Spanish territory.
(Additional reporting by Foo Yun Chee and Alastair Macdonald; Editing by Mark Potter)