Donald Trump has suggested Spain (which is in Europe) build a wall across the Sahara desert (which is in Africa)

Josep Borrell said the US President (pictured) had insisted the type of barrier he has vowed to build along America's border with Mexico would work for Europe as well. Photo / Getty

Donald Trump suggested building a wall across the Sahara to tackle Europe's migrant crisis, Spain's foreign minister has claimed.

Josep Borrell said the US President had insisted the type of barrier he has vowed to build along America's border with Mexico would work for Europe as well.

Spain has become a key entry point for migrants who follow a 'Western Mediterranean Route' to Europe from Northern Africa. Many of the refugees are from sub-Saharan nations.

The former President of the European Parliament did not reveal when Trump had put forward his radical idea. But diplomatic sources suggested it had been in June when he flew to the States in a trip coinciding with the visit to the White House of the Spanish King and Queen.

Mr Borrell revealed Trump's Saharan wall 'solution' during a lunch in Madrid organised by cultural association Club Siglo XXI, which was formed in 1969 and is known for holding prestigious debates, conferences and forums.

Spanish daily El Pais said he had made it clear he disagreed with Donald Trump's diagnosis but insisted a policy had to be put in place to deal with the fact Africa would double its population in the next 20 years.

Mr Borrell also took the opportunity at the event in Madrid to attack Italy's right-wing Interior Minister Matteo Salvini who made his mark in the job by turning away a boatload of more than 600 African refugees in June and leaving Spain to pick up the pieces.

Baker's son Mr Borrell was appointed Foreign Minister in June when Pedro Sanchez became PM after winning a no-confidence motion he proposed against the country's former right-wing leader Mariano Rajoy.

Trump, meanwhile, said earlier this month he was considering using military resources to finish construction of his long-promised border wall instead of relying on Congress to fund it, the MailOnline reported.

Spain has become a key entry point for migrants who follow a 'Western Mediterranean' route to Europe from Northern Africa. Many of he refugees are from sub-Saharan nations. Photo / AP

He has insisted Mexico will pay for it since he started touting the idea of a border block during his presidential campaign. Mexican officials have consistently said they will not pay.

Spain has overtaken Italy and Greece as a popular entry point for migrants.

EU border agency Frontex registered 12,500 arrivals in August - with 6,500 of them reaching Spain's Mediterranean coastline and making the country the main EU port of arrival for migrants for the second month running.

Most of those reaching Spain were from Morocco, Guinea and Mali.

Nearly 30,000 migrants used the Western Mediterranean route in the first eight months of the year according to Frontex, double the figure for last year.

New research has found 2 million migrants have arrived in Europe by crossing the Mediterranean Sea since 2009.

According to the Pew Research Center, the paths refugees have taken have changed over the years.

The route most travelled this year was from Morocco to Spain - in stark contrast to previous years when this western route was the least travelled migration path.

Pew Research Center drew on data from Europe's border and coast guard agency Frontex and the United Nations High Commissioner for Refugees.

From 2009 to the end of 2917, 89,000 migrants had arrived along Spain's south coast using the western route.

But between January and August along, there have been 28,000 arrivals.

This was greater than both the Africa to Italy 'central route' and Turkey to Greece 'eastern route' both of which saw 20,000 arrivals.

Pew Research Center said this was partly due to Spain accepting migrant rescue ships in its docks when other countries had denied them entry.

It added that 2018 had proved to be a particularly deadly year for Mediterranean crossings between Africa and Italy.

For every 18 migrants who reached Italy by boat during the first seven months of this year, one drowned attempting that crossing, UN figures showed.

Since 2009, a million refugees have crossed the Mediterranean from Syria and Iraq while a further 620,000 have come from sub-Saharan Africa and nearly 390,000 from Asian countries including Afghanistan, Pakistan and Bangladesh, Pew Research Center reported.