Britain's ambassador to Madrid has lodged a formal protest with Spanish authorities over "disproportionate border checks" between Spain and the tiny British enclave of Gibraltar.
The U.K. government said Tuesday that top diplomat Giles Paxman had visited Spain's foreign ministry to seek an explanation for suggestions that fees would be levied at the border between the British territory and Spain.
Spain has long laid claim to Gibraltar, and the tiny territory on the southern tip of the Iberian peninsula is the source of occasional diplomatic friction between Madrid and London.
The latest spat involves an artificial reef being built in Gibraltar that Spain says is hurting its fishermen. It has floated the idea of charging people entering and leaving Gibraltar 50 euros ($66 US) as compensation.
On Monday, Gibraltar's top official accused Spain of acting like North Korea after suggesting it could impose such a fee.
Such fees would violate European Union freedom of movement rules, Gibraltar Chief Minister Fabian Picardo told BBC radio on Monday, adding "hell would freeze over" before the reef would be removed.
"What we have seen this weekend is saber-rattling of the sort that we haven't seen for some time," Picardo said, describing threats of border fees as "more reminiscent of the type of statement you'd hear from North Korea than from an EU partner."
Under Spain's former Socialist government, relations between Madrid, London and Gibraltar eased greatly. But in an interview published Sunday in Spanish newspaper ABC, Spanish Foreign Minister Jose Manuel Garcia-Margallo said the "playtime" of that era was over.
Britain's foreign secretary said late Monday that he had spoken with Picardo to express solidarity with the territory's residents.
"The U.K. stands shoulder to shoulder with the people of Gibraltar at this time of increasing Spanish pressure and rhetoric," William Hague said in a statement, repeating that the U.K. had pledged "not to compromise on British sovereignty over Gibraltar."
But he also nodded to the fact — so far — the talk of sanctions had not amounted to real clampdown on the territory. "We agreed that it was important to respond to actions, not rhetoric," he said.
Disputes over issues including customs, fishing rights, Gibraltar's offshore banking practices and smuggling have long embittered relations between the two nations.