The Sahara is one of the world’s most inhospitable regions, yet migrants frequently cross it in the hopes of reaching the Mediterranean sea, and ultimately, Europe.

Following a wave of racist violence in the Tunisian city of Sfax, some sub-Saharan Africans have fled to a militarised buffer zone bordering Libya.

Officials in Libya have also accused Tunisia of dumping hundreds of migrants over the border in the desert - with no food, water or shelter.

Both Libya and the UN say they have rescued migrants from the border.

Tunisia - which recently signed a migration pact with the EU - has not commented on Libya's allegations.