US President Donald Trump leaves the Oval Office at the White House. Picture: REUTERS/KEVIN LAMARQUE
US President Donald Trump leaves the Oval Office at the White House. Picture: REUTERS/KEVIN LAMARQUE

Just when you thought Donald Trump could not do anything crazier, he has asked the Spanish government to build a wall across the Sahara desert to keep Africans out of Europe.

Trump, who has previously described some African countries as "sh*tholes", made the suggestion to the Spanish foreign minister Josep Borrell, the Guardian reported.

When Borrell pointed out that Sahara was vast, Trump replied "The Sahara border can’t be bigger than our border with Mexico.”

Trump campaigned for president on the promise that he would wall off Mexico to stop illegal immigrants entering the US.