British government officials said they would protest the latest "provocative and dangerous" Spanish moves at the highest level. It wasn't clear if King Juan Carlos or Prime Minister Mariano Rajoy was the intended target for a new diplomatic initiative by British officials in Brussels and London.
A simmering dispute over Gibraltar's future has come to the boil frequently over the past few months. The war of words has come as a handy distraction for Rajoy's coalition as it battles economic downturn in Spain. For British Prime Minister David Cameron, the row over Gibraltar has oddly rekindled memories of Britain's row with Argentina over the Falkland Islands in 1982, which led to war and Argentine defeat.
Much to London's annoyance, Spain supports Argentina's continuing claim on the Falklands.
The Falklands war boosted former Conservative Party Prime Minister Margaret Thatcher's standing in British politics at the time. Resonances of the Falklands conflict have both helped and hindered the Conservative Cameron, aiding his image-builders but also pushing the prime minister toward a tougher line with Spain.
Both prime ministers seem anxious not to be giving an inch to the other side, with the result that the war of words appears to be getting worse, not mellowing or opening channels of reasoned diplomacy, analysts said.
Britain reacted angrily to an incident this week involving British Royal Navy vessels and a Spanish Guardia Civil patrol boat.
Ministry of Defense officials in London accused the patrol boat of "maneuvering in a provocative and dangerous manner in the vicinity of Royal Navy vessels," the BBC reported.
No shots were fired in the incident but the patrol boat and a Gibraltar Defense Police boat were involved in "a minor collision."
Speaking in the House of Lords Thursday, Conservative peer Baroness Hooper said "guns were pointed at each other" during the incident Wednesday. In Madrid, the Spanish daily El Pais said it interviewed Gibraltar residents who complained of being painted "in a bad light."
In September, European Union inspectors visited Gibraltar to investigate endemic border rows, with British and Gibraltar officials complaining of excessive Spanish checks on border traffic. Spanish officials say the checks are necessary to combat smuggling from Gibraltar, especially of cigarettes.
Spanish workers with jobs in Gibraltar also complained of delays that put their employment at risk.
The EU visit was called a fiasco by critics who said it defeated the very purpose it set out to serve when Brussels announced the visit, removing any element of surprise.
The dispute has soured relations between the two EU member countries and also built up pressure on jobless Spanish EU citizens said to be entering Britain in large numbers. So far there hasn't been a major incident targeting Spanish workers in Britain but analysts say tensions have built up in the aftermath of tabloid headlines over Gibraltar.