Migrant flight through Libya

In the image above, a desert road marks the hazy border between Libya, in the foreground, and Algeria, stretching into the distance.

It has always been a challenge to seal Libya's more than 2,000 km-long southern border, but since the revolt that overthrew Libyan leader Muammar Gaddafi three years ago, it appears few are even trying.

The uprising against Gaddafi emptied Libya's arsenals, flooded the region with guns and dismantled much of the state apparatus.

Tripoli, far to the north, has reduced funding to border troops as it grapples with a budget crisis due to protests that shut down oil exports, and well-organised smuggler networks operate along the frontier.

His face covered, a Libyan smuggler talks with a group of illegal migrants in the border town of Ghat, before taking them through the desert to the north of the country.

Border officials say up to 200 Africans cross the border strip here every day, most headed to the Mediterranean coast for the onward trip to Europe by boat.

Smugglers not only shepherd migrants, they also ship items such as petrol and wheat south into sub-Saharan Africa or west into Algeria, profiting off the lavish state subsidies that keep such goods cheap in Libya.

His eyes piercing and bloodshot, an African emigrant is covered with a shawl at a detention centre in Zawiya.

Many others, however, have passed through without capture. According to the Italian coast guard, at least 50,000 people have crossed from North Africa to Italy by boat so far this year, already far exceeding the 40,000 who arrived in the whole of 2013. Most came over land from sub-Saharan Africa, via Libya.