Donald Trump encouraged Spain to build a wall in the Sahara desert to tackle the Mediterranean migration crisis, according to the Spanish foreign minister.

Josep Borrell made the comments during an event in Madrid this week, Spanish newspaper El Pais reported - with the minister stressing he did not support the suggestion.

The US President is said to have insisted: "The border with the Sahara cannot be bigger than ours with Mexico."

A spokesperson for the Spanish foreign ministry confirmed to The Guardian that Mr Borrell made the comments, but added that they would not be making any further comment on the remarks.

A border wall between the Mexico and the US to tackle illegal immigration was one of President Trump's key campaign promises during the 2016 election.

While the White House has made some initial efforts to get the project up-and-running, the Trump administration has struggled to secure congressional funding to pay for the wall - which experts have suggested could cost between $10 billion and $20 billion.

Although Spain holds two small enclaves in north Africa, the Sahara desert itself is spread across 11 countries and is thousands of kilometres long.

Spain has seen an estimated 33,000 migrants and refugees arrive by sea across the Mediterranean since January, according to the UN Migration Agency - making it the 'leading destination' for Mediterranean migrants, outpacing both Greece and Italy.

In his comments, Mr Borrell also suggested that the migration issue was not 'an economic problem but an emotional one'.

"European societies are not structured to absorb more than a certain percentage of migrants," he suggested.