LONDON — Britain on Wednesday said it would make a formal protest to Madrid after a Spanish warship entered the British waters around Gibraltar and disrupted a Royal Navy exercise.
A Foreign Office spokesman said the incident would be raised to a "high level."
Gibraltar, a tiny piece of land on the southern tip of Spain and under British control for 300 years, is a major bone of contention between the two European powers.
Tensions worsened last year, when Spain accused Gibraltar of disrupting its fishing by creating an artificial reef.
Madrid in turn tightened controls at the border between Gibraltar and Spain, causing huge delays. It said the additional checks were needed to prevent tobacco smuggling.
"There was an incursion into British waters near Gibraltar by the Spanish Navy on 18 February, during a Royal Navy exercise," said the Foreign Office spokesman.
"We are raising this at a high level with the Spanish government and will be issuing a formal protest," he continued. "Neither this incident nor other incursions change the fact of UK sovereignty over British Gibraltar territorial waters."