The Spanish outposts of Ceuta and Melilla in northern Morocco, which have the European Union’s only land borders with Africa, are tempting launch pads for clandestine immigration to continental Europe.
Ceuta, a former Roman colony of 85,000 people, measures about 18 square kilometres (seven square miles) and lies just across the Strait of Gibraltar from Spain.
It was captured by the Arabs and the Portuguese and has been under Spanish sovereignty since 1640.
Melilla, measuring about 200 square kilometres, is perched on the eastern edge of Morocco’s Mediterranean coast, and has been under Spanish control since 1497.
It has a diverse population of about 85,000, of which around half are Muslims, and thousands of Moroccans go there to work and shop every day.
Thousands of migrants have attempted to cross the 12-kilometre (7.5 mile) frontier between Melilla and Morocco, or the eight-kilometre border at Ceuta, by climbing the border fences, swimming along the coast or hiding in vehicles.
More than 350 migrants stormed the six-metre-high double fence at Ceuta on Monday, just days after nearly 500 migrants made it over, one of the biggest entries since the barrier was reinforced in 2005.
The two territories are protected by fences fortified with barbed wire, video cameras and watchtowers. Migrants have died or been injured trying to breach the barriers.
On January 1 more than 1,000 migrants from sub-Saharan Africa tried to scale the fence at Ceuta during a violent assault in which one officer lost an eye.
Both exclaves were conquered as part of a strategy by Catholic kings of establishing advance posts of Christendom on the African continent following the expulsion of Moors and Jews from Spain in 1492.
Claimed by Morocco, the two cities have long been a flashpoint in diplomatic relations between Madrid and Rabat, with Madrid insisting that both are integral parts of Spain.
Both port cities have developed as military and trade centres linking Africa to Europe, and since the 1990s have enjoyed a status similar to other autonomous areas such as the Basque region and Catalonia.
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