David Cameron had been due to address thousands of people in the rocky outcrop, which fears that a vote to exit the European Union in next week's referendum will leave it at the mercy of Spain. (File Photo)
British Prime Minister David Cameron cut short a historic visit on Thursday to Gibraltar where he had planned to address a pro-EU rally, after a member of parliament was murdered in England.
Jo Cox, a 41-year-old mother-of-two from the opposition Labour Party who supported the campaign to remain in the EU, was killed in broad daylight in a northern English town.
"We've lost a great star, a great campaigning MP," Cameron told BBC News shortly after landing in the tiny overseas British territory on Spain's southern tip.
The prime minister had been due to address thousands of people in the rocky outcrop, which fears that a vote to exit the European Union in next week's referendum will leave it at the mercy of Spain.
The Rock, as it is known, has long been a source of friction between London and Madrid, which wants it to come back under its control centuries after it was ceded to Britain in 1713.
But following the attack on Cox all campaigning for the crucial June 23 vote was suspended.
Cameron only stayed in Gibraltar for a few hours, holding a short meeting with the territory's chief Fabian Picardo as well as pro-EU campaigners before flying out again.
Anger in SpainCameron's trip had drawn huge excitement in Gibraltar, where the last serving British prime minister to visit was Harold Wilson in 1968, and Picardo described it as "historic".
But it also drew anger from Spain.
"The government doesn't like it that Mr Cameron is going to Gibraltar," acting Spanish prime minister Mariano Rajoy said in a radio interview.
"What is being debated is whether the United Kingdom stays in the European Union -- as I hope it will -- or leaves the European Union.
"The campaign for this should be done in the United Kingdom and not in Gibraltar."
But following news of Cox's death, Rajoy sent his condolences to Cameron, condemning what he described as a "savage attack".
The 33,000-strong territory is eyeing the upcoming vote with increasing alarm, particularly as the latest opinion polls indicate a majority of Britons want to leave the EU.
At stake is a thriving services-based economy that relies in large part on access to the EU's single market, and the sovereignty spat with Spain.
Gibraltar ThreatenedPicardo has said he is worried Spain may seize the opportunity of a Brexit -- which would leave it without EU protection -- to threaten the land border between the two, a long-time flashpoint in the sovereignty row.
Spain's dictator Francisco Franco went as far as closing the crossing in 1969, all but stranding inhabitants who had to rely on air and boat links until it was fully reopened in 1985.
Relations have ebbed and flowed since, but the past four years have seen tensions resurface under Spain's conservative government.
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.
And last week, Spanish Foreign Minister Jose Manuel Garcia-Margallo revived the idea of sharing sovereignty over the Rock with Britain in the event of a Brexit.
Such a proposal had been sketched out between the two countries in 2001 and 2002, but rejected after Gibraltarians voted against it in a referendum.