At least seven migrants, including a woman, drowned Thursday while trying to swim to the Spanish enclave of Ceuta from a beach in neighbouring Morocco, officials in both countries said.
The deaths come as Morocco struggles, under pressure from Spain, to limit the rising tide of sub-Saharan migrants heading to its northern shores in a desperate quest to reach mainland Europe.
Hundreds of migrants headed out to sea from the Moroccan town of Fnideq at 6 am (0600 GMT) in a mass attempt to circumvent the six metre (20 foot) barriers that mark the land border with the Ceuta enclave, Spanish and Moroccan officials said.
Authorities in Fnideq said around 200 migrants made the attempt.
Authorities in Ceuta said "around 400 sub-Saharans" had taken part in the desperate bid to reach EU territory, braving the strong currents of the Strait of Gibraltar.
Moroccan coastguard vessels picked up 150 of the migrants, while the rest turned back to shore, the official MAP news agency reported.
A local representative of the Moroccan Association for Human Rights said eight migrants had drowned.
"This drama shows once again the risks taken by illegal migrants, who put their lives in danger," the authorities in Fnideq said.
Ceuta is the northernmost point on the coast of northwest Africa and lies just 15 kilometres (9 miles) across the strait from the Spanish mainland.
Ceuta and Spain's other north African enclave Melilla have the European Union's only land borders in Africa.
They are seen as stepping stones to a better life in Europe for sub-Saharan migrants, who often risk their lives attempting to enter the tiny Spanish enclaves, either by sea or by storming the barriers that separate them from Morocco.
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On Sunday, the bodies of five presumed migrants thought to have been trying to reach Spain in an inflatable boat, were found in the Nador area of Morocco's Mediterranean coast, near Melilla.
According to the Rif Human Rights Association, more than 40 migrants died trying to reach Ceuta or Melilla from Morocco over the past two years.
Many more attempt the perilous journey across the Strait of Gibraltar, often in overloaded makeshift boats.
Spain is just one of the southern European countries facing a mounting influx of African migrants and asylum-seekers.
Earlier this week, Italy said the number of asylum-seekers landing on its shores rose tenfold in January, compared to the same month last year.
Rome launched a military and humanitarian response last October, after hundreds of migrants drowned in two shipwreck tragedies near the Italian Mediterranean island of Lampedusa.
Faced with the same problem, Spain last year began to put barbed wire along Melilla's 11-kilometre (seven-mile) border fence in a bid to deter the migrants, drawing criticism from human rights groups.
The authorities in Tangiers, Morocco's main northern city, also announced that they were beefing up surveillance along the coast, where they claim to intercept scores of migrants trying to reach Europe each week.
Morocco estimates there are around 30,000 illegal immigrants on its soil, most of them from sub-Saharan Africa.
In early January, the government launched an operation to regularise their situation and grant them residency permits, in the face of allegations that several migrants had died at the hands of police in 2013.