The Spanish government has called for shared sovereignty over Gibraltar in the face of Britain's decision to leave the European Union.
The British Overseas Territory voted overwhelmingly to Remain, with 95.9% of voters backing the status quo. The enclave at the entrance to the Mediterranean relies heavily on its open border with Spain for trade.
But acting Spanish foreign minister Jose Manuel Garcia-Margallo said he hoped "co-sovereignty" of Gibraltar and "the Spanish flag on the Rock" were much closer to happening in the wake of the vote, in a radio interview cited by Reuters.
Gibraltar's chief minister Fabian Picardo, who shared a platform with Foreign Secretary Philip Hammond in May in support of the Remain campaign, had earlier tweeted: "We have surpassed greater challenges. It is time for unity, for calm and for rational thinking. Together and united we will continue to prosper."
He is due to give a speech on this afternoon.
Julie Girling, the South West England and Gibraltar Conservative MEP - who also backed Remain, said; "I am deeply sorry that the people of the UK have chosen this leap in the dark. I believe future generations will question our wisdom.
"The EU has many faults, of course, but I remain convinced that we would be safer, stronger and better off by remaining a member."
Gibraltar was ceded to Britain in 1713 in the Treaty of Utrecht. But over past decades Spain has made various noises about taking it back, including a 2013 dispute which saw border checks reintroduced - causing long delays - in a row over an artificial reef.
A referendum on joint sovereignty in 2002 saw 98.48% of citizens of the territory back remaining British.
The Gibraltar Chamber of Commerce had also backed the Remain campaign, calling Brexit "a leap in the dark".
In a letter to members on Tuesday, the chamber's board said the open border with Spain had helped the territory's financial services industry develop.
It added: "Each weekday half of Gibraltar's workforce crosses the border to get to work. Of the 12,000 people who cross the frontier, around 7,000 are Spanish and the remaining 5,000 are other Europeans. Without this open frontier many businesses in Gibraltar would not have a workforce."
In May Mr Picardo told a news conference that Brexit supporters should reflect on the fact that a leave vote would see joint sovereignty "back on the table".
He said: "Ironically, somebody who believes they are being patriotic and supporting Gibraltar by voting to leave the European Union will be bringing about, actually, Gibraltar having to face, once again, the prospect of joint sovereignty with Spain, something which most of the friends of Gibraltar in the Brexit side of the argument fought tooth and nail against at the time it was last tabled by a Labour government in the early part of the 21st century."