Britain is facing the prospect of being taken on by a joint Spanish and Argentine campaign over the disputed territories of Gibraltar and the Falklands.
Spain may take its row over Gibraltar to the United Nations, according to reports in Spanish newspaper El Pais.
According to the paper, the country’s foreign minister Jose Manuel Garcia-Margallo is scheduled to travel to Buenos Aires to meet his Argentinian counterpart, Hector Timerman, next month.
During this meeting, the paper says, Spain will also explore the possibility with Argentina of a “united front” at the UN, concerning Gibraltar and the Falklands.
Argentina is immersed in its own dispute with Britain over the sovereignty of the Falklands, which Britain has ruled since 1833.
The newspaper’s sources do not specify whether Spain will ask the UN to back a request for Britain to give up sovereignty of the territory, or adhere to certain agreements.
Aside from the Security Council, Spain could also take its matter to the UN General Assembly or the International Court of Justice.
Centuries of friction over the Rock – a British overseas territory to which Spain lays claim – have reignited following delays and queues of several hours at the outpost’s border with Spain, and Madrid’s threats to impose a 50 euro (£43.30) fee on every vehicle entering or leaving Gibraltar.
Madrid has also complained that an artificial reef being built by Gibraltar into the Mediterranean will block its fishing vessels.
The reported change of tack by Spain could further increase diplomatic tensions.
Prime Minister Mariano Rajoy has said that Spain will take “all necessary measures” to defend its interests in Gibraltar.
His comments this week came as Britain sent warship HMS Westminster and two other vessels to the British territory, which the Ministry of Defence said was part of a “long-planned” training exercise.