Agadez - The start of the desert trek from Africa to Europe

More than 13,000 migrants have arrived in Italy so far this year by sea, crossing the Mediterranean from North Africa.

But before they reach Libya, many migrants will have undertaken a perilous journey of up to six days across the Sahara in extreme temperatures.

The jumping-off point for the desert trek is Agadez, in Niger, through which 100,000 migrants are estimated to have passed in the last year alone.