"Get back, get back," the Tunisian soldiers in olive fatigues push and swear at 200 Sudanese. They don't and their dialect pulls others into the chant, behind the frenzied waving of cardboard slogans. "Down with Bashir! Ambassador out, ambassador out, take us home, ambassador fly, ambassador fly out!" The Sudanese mob waves in a frenzy, breaks up again. "Allah akbar, Allah akbar, Allah akbar." 

"It's always like this in the refugee camp. Yesterday it was the Ghanaians, then the Ugandans. Little riots, they're getting desperate when they realise they are poor-country nationals who are marooned," an aid worker tells me.

A thousand hysterical Bangladeshis are chanting a slogan no one can understand, marching nowhere, purposefully. They shout until they scream. Uncountable thousands head in unwashed swirls to the soup kitchen. Coughing, shouting, the smell of gasoline and faeces — the taste of a humanitarian catastrophe. South Asians and Africans lie on their backs in thickets of trash. 

The UAE is building a halal encampment for ethnic Libyan refugees by the border gates. At the exits, Islamists with curling ringlet beards greet each refugee with a plastic bag containing cookies and a carton of juice. At the entrance there is only quiet. 

"What started as a revolution here has turned into a war there," says the Tunisian border guard. "It's nothing do with us. It's a civil war, not our revolution any more."