According to foreign minister Josep Borrell, the US president insisted the barrier would help tackle Europe’s migrant crisis.
Borrell did not reveal when the leader floated the idea, but sources suggest it was in June, when Borrell visited Washington during the White House visit of King Felipe and Queen Letizia.
Borrell revealed Trump’s Saharan wall ‘solution’ during a lunch in Madrid organised by cultural association Club Siglo XXI, which is known for holding prestigious debates, conferences and forums.
According to El Pais, Borrell ‘made it clear’ that he disagreed with Trump’s diagnosis but insisted a policy was needed to deal with the fact that Africa would double its population in the next 20 years.
Borrell also attacked Italy’s right-wing Interior Minister Matteo Salvini for turning away a boatload of more than 600 African refugees in June and leaving Spain to deal with it.
Spain is now the most popular entry point for migrants in the EU, accounting for 6,500 arrivals out of 12,500 in August.
Most arriving in the country came from Morocco, Guinea and Mali.
Borrell became the new foreign minister in June when conservative Prime Minister Mariano Rajoy was ousted in a vote of no confidence, paving the way for PSOE leader Pedro Sanchez to take on the role.