For the fifth straight year at least 1,500 migrants have perished in the Mediterranean, with the route between Libya and Italy being the deadliest, claiming the lives of one in 19, the U.N. migration agency said on Friday.

Spain, which has overtaken Italy as the preferred destination, has registered nearly 27,000 migrants so far this year, almost more than all of last year, the International Organization for Migration (IOM) said. Almost 20,000 of them arrived by sea, as good weather allowed more crossings on the short route across the Strait of Gibraltar and a recent crackdown by Libyan authorities had led migrants to choose other routes. In all, about 55,000 migrants have reached European shores so far this year, against more than double that number at this time last year, 111,753, it said.

Italy, Greece and Spain have been on the frontline of the refugee crisis, with Europe deeply divided over how to share the burden of the massive influx of people seeking a new life in Europe. Italy, whose new far-right government has closed its ports to rescue vessels, has had about 18,130 migrants arriving by sea from Libya this year, with the rest going to Greece, Malta and Cyprus.

"It's important to note two things: one is that despite incredibly low numbers arriving to Italy, the per capita death or the rate of death per 1,000 people may be at its highest point since the emergency began," IOM spokesman Joel Millman told a Geneva news briefing.

Referring to the 1,500 death toll, he said: "It's only once in the previous four years [that] this mark has been reached later than this date in July and that was in 2014 when the emergency was really just starting".

More than 600 African migrants forced their way through the heavily fortified border fence separating the Spanish North African enclave of Ceuta from Morocco on Thursday, using circular saws, shears and mallets to cut through the wire.

"What we can say is that the first indications that we are getting from the Spanish authorities is that it is the West African migrants that were most prominent crossing into Libya in the past couple of years who seem to be choosing Spain as their route now," Millman said. The death rate on the western Mediterranean route to Spain is about one in 70 migrants, he added.

The western Mediterranean route from Morocco to Spain could become the most popular pathway for migrants. While the land route through Ceuta or the second Spanish enclave of Melilla is popular, many more migrants are increasingly reaching Spain by boat. All options pose risks, of drowning, abuse by smugglers or even kidnapping. A Europol operation detailed last month uncovered a trafficking network which smuggled more than 100 children from Morocco to Spain, charging them each 2,000 to 8,000 euros ($2,350-$9,400). A second gang kidnapped young migrants and forced their families in Morocco to pay 500 euros for their release, the EU's law enforcement agency said.