Gibraltar airport was evacuated on Sunday and the tiny British territory's border with Spain closed for several hours because of a suspicious piece of luggage on a London-bound plane, police said.

The police were called to the airport in early afternoon after a baggage handler thought he saw smoke coming from a piece of luggage that was being put onto an easyJet flight that was getting ready for departure to London's Gatwick airport, a police spokesman said.

Just across the sea from the sunny tourist beaches of southern Spain where many Europeans spend their Christmas holidays, a violent crisis is intensifying on Europe's borders with Africa.

Every week, hundreds of Africans try to scramble over the high fences that encircle Ceuta and Melilla, two Spanish-ruled enclaves on the northern tip of Morocco.

Spain rescued Tuesday nearly 500 African migrants trying to enter the country by boat while hundreds more tried to scramble over a border fence into the Spanish territory of Melilla.

Spain's coastguard said it picked up 470 sub-Saharan Africans who were crossing the Strait of Gibraltar in 49 small boats, part of a surge of migrants across the Mediterranean to Europe's southern shores.

Spain's coastguard said it had rescued 267 sub-Saharan African migrants on Monday, including 39 women and three children who were among those trying to reach Spanish soil on a flotilla of small boats.

Spain's coastguard said it had rescued 267 sub-Saharan African migrants on Monday, including 39 women and three children who were among those trying to reach Spanish soil on a flotilla of small boats.

The migrants were picked up in the Strait of Gibraltar and taken to Tarifa, Spain's southernmost port, a spokesman for the coastguard told Agence France Presse.

Spain accused Britain on Friday of "unacceptable interference" for launching a diplomatic protest over a maritime dispute off the contested British territory of Gibraltar.

It was the latest in a long string of diplomatic skirmishes over the tiny Mediterranean peninsula which has been governed by Britain since 1713 but is claimed by Spain.

The British government summoned the Spanish ambassador to the Foreign Office in London on Thursday over the actions of a Spanish naval vessel near Gibraltar.

A Spanish navy ship tried to divert two commercial vessels heading to the port of Gibraltar by wrongly claiming they were in Spanish waters, Europe Minister David Lidington said. 

Britain should take a tougher stand towards Spain in disputes over Gibraltar, including using legal action and more diplomatic protests, a parliamentary committee urged on Tuesday.

Spain disputes British sovereignty over the peninsula, which has long been a point of contention in relations between the two countries, with tensions increasing over the last year.

Spanish activists on Monday removed part of a controversial artificial reef which was built in disputed waters near Gibraltar despite objections from Madrid.

The two-tonne concrete block was one of 70 that Gibraltar dropped into the sea in July 2013 saying it was creating an artificial reef that would boost fish populations.

The British government summoned the Spanish ambassador to London on Wednesday to explain a fresh "incursion" by Spanish vessels into Gibraltar's territorial waters.

Ambassador Federico Trillo was hauled in to explain why a Spanish state research vessel and its police escort entered the waters off the tiny British peninsula on Tuesday, the Foreign Office said in a statement.