The Spanish are guilty of an "outrageous" violation of British sovereignty by sending boats and helicopters into UK waters in Gibraltar, it has been claimed.
The Government of Gibraltar said they are "astonished and appalled" after Spanish police chasing criminals made several incursions into British waters in the past two days.
The Royal Navy helped escort the Servicio de Vigilancia Aduanera (SVA) - the Spanish police's drugs and money laundering squad - out of the waters following the international row.
The Chief Minister of Gibraltar, Fabian Picardo, said the incursions amounted to an illegal and dangerous display of "bravado".
He said: "I am sure I am speaking for the whole of Gibraltar when I say that we consider this has been a serious and unnecessary failure on the part of the Spanish SVA which has had outrageous consequences in respect of the violation of our sovereignty."
In one incident the Spanish are understood to have been pursuing smugglers who were dumping suspected bales of drugs off the side of a fast-speed inflatable boat when they travelled through British waters.
They also allegedly flew a helicopter over the Sandy Bay beach area of the island in a move branded "extremely dangerous" by the Gibraltan Government.
In another incident the Spanish allegedly boarded a boat and questioned crew.
Mr Picardo said police in Gibraltar should have been asked to assist in catching the criminals once the chase looked like it would go into British-controlled waters.
He blamed the failure to do so for the escape of one suspected drug smuggler.
He said: "It's actions have ultimately resulted in the escape of a criminal that citizens on both sides of the frontier would have liked to have seen arrested and imprisoned for his drug trafficking."
He added: "We all want to stop the drug smugglers. It beggars belief that the SVA have acted in this way that, in effect, has allowed a criminal who should be behind bars to get away.
"The whole of Gibraltar will be outraged at their failure to cooperate in a way that would have better assisted to capture the criminals in question."
Mr Picardo said he expects British ministers to pursue the matter.
Foreign Office Minister Hugo Swire said: "On 9 August Spanish state vessels repeatedly entered British Gibraltar territorial waters without notifying Gibraltarian authorities.
"We understand that the Spanish were in pursuit of vessels who may have been committing crimes. However it is completely unacceptable and unlawful under the international law of the sea to enter our waters without notifying us.
"These repeated incursions into British Gibraltar territorial waters are a clear violation of UK sovereignty by another EU country and we will be raising this as a matter of urgency with the Spanish authorities."