MADRID (AP) — The British territory of Gibraltar said a Spanish navy patrol ship entered its waters Tuesday amid the simmering tensions between Spain and Britain over Gibraltar's future after Brexit.

The territory's government announced the alleged incursion by the Spanish ship Infanta Cristina on its official Twitter account. It also posted a short video of the corvette.

Spain, which has for centuries demanded a return of sovereignty over the enclave on its southern tip, doesn't recognize Gibraltar's territorial waters.

A Spanish Ministry of Foreign Affairs official said the Infanta Cristina was conducting a routine patrol in Spanish waters.

A Ministry of Defense official added that Tuesday's patrol was no different than others conducted on a weekly basis to monitor migration or drug trafficking across the Gibraltar Strait. Both spoke anonymously in line with internal rules.

Britain is annoyed with Spain and the European Union because the European Union has said Spain should have veto rights on any agreements regarding Gibraltar during the negotiations on Britain's exit from the EU.

The Brexit dispute made Tuesday's occurrence sensitive, but Spanish fishing and navy ships frequently pass close to Gibraltar, often provoking spats over alleged incursions.

Tuesday's was the seventh incursion by a Spanish navy ship this year, according to Gibraltar's government. It said that one of the two patrol vessels that Britain's Royal Navy keeps in Gibraltar chased the Spanish ship off.

"The Royal Navy challenges all unlawful maritime incursions into British Gibraltar Territorial Waters — and did so again on this occasion," the Foreign Office said in a statement.

Tensions soared after Gibraltar built an artificial reef in 2013 that Spain said hurt its fishermen. Spain retaliated by beefing up border security, creating delays. Britain also accused Spanish vessels of a series of "irresponsible" incursions into Gibraltar waters.

In July, Spain's Foreign Ministry summoned the British ambassador to protest what it described as reckless behavior by a Gibraltar police boat toward a Spanish police vessel.

AP writers Jill Lawless and Danica Kirka in London contributed to this story.