Police stopped more than 1,600 migrants trying to cross the border from Morocco into the Spanish territory of Ceuta on Tuesday, an official said.

The migrants were the latest in a tide of desperate people trying to breach the frontiers with Ceuta and Melilla, Spanish-held cities perched on the north African coast.

The bodies of five presumed migrants thought to have been trying to reach Spain were found on Sunday on northern Morocco's shoreline, local authorities said.

"The bodies of five probably illegal migrants, four of them from Senegal, were washed up from the Mediterranean" in the Nador area, MAP news agency cited officials as saying.

King Juan Carlos told Britain that it was not in Spain's interest to take back Gibraltar as it would trigger claims from Morocco for Spanish territories, newly declassified documents from the 1980s show.

The king admitted in a private conversation with the then British ambassador to Madrid, Richard Parsons, that "it was not to the advantage of Spain to recover Gibraltar in the near future".

Prime Minister David Cameron said Wednesday that Spain has promised there will be no repeat of an "extremely serious" incident in which its officials searched British diplomatic bags at the Gibraltar border.

Cameron's assurances came despite claims from lawmakers that Spain was acting like "the Zimbabwe of Robert Mugabe" in the latest in a string of bad-tempered confrontations between London and Madrid.

Britain said Wednesday it has received assurances from Spain that there will be no repeat of an incident in Gibraltar where Spanish officials searched British diplomatic bags.

The British embassy in Madrid lodged a formal protest with the Spanish government on Monday following what it described as a "serious infringement" of diplomatic protocol.

The EU executive on Friday said it had found no proof of British claims that Spain had violated European Union rules on border and customs checks at Gibraltar's border.

"The Commission has not found evidence to conclude that the checks on persons and goods as operated by the Spanish authorities at the crossing point of La Linea de la Conception have infringed the relevant provisions of Union law," a European Commission statement said.

Britain said Friday it would complain to Spain about a Spanish research boat that it said unlawfully entered disputed waters off Gibraltar, reviving a simmering diplomatic dispute.

Britain's foreign ministry said the oceanographic survey vessel accompanied by Spanish police boats made unlawful incursions on Wednesday and Friday into waters off the British overseas territory on the southern tip of Spain.

Spain demanded Thursday that Gibraltar Chief Minister Fabian Picardo prove accusations he made at the United Nations that Spanish police had fired shots at a Gibraltarian man in the contested waters surrounding the British territory.

During an address to the United Nations in New York on Wednesday Picardo accused the Spanish government and the media of waging a "campaign of incitement to hatred through lies" against Gibraltar.

Gibraltar on Tuesday called on the United States to use its diplomatic heft to help end a bitter dispute over its sovereignty, accusing Spain of "bullying" the tiny British territory amid a flare-up of tensions.

"The United States must stand for the right of people to determine their own future," Gibraltar's head of government, Chief Minister Fabian Picardo said.

Spanish authorities on Monday rescued 10 African migrants crossing the Strait of Gibraltar in a rubber dinghy in another incident highlighting the perils of trying to enter Europe illegally, after last week's fatal shipwreck in Italian waters.

Rescue teams received a call in the morning from the dinghy transporting 10 men, all from sub-Saharan Africa, saying "they had left the Tangiers region (northern Morocco) at 1:00 am" local time, a spokesperson from the rescue services said.