The Greek-managed bulk carrier Irene E.M., which was hijacked by Somalia pirates in the Gulf of Aden. Photo / AP

The Greek-managed bulk carrier Irene E.M., which was hijacked by Somalia pirates in the Gulf of Aden. Photo / AP

The lucky ones come with their families, others appear out of the thorn bushes, walking alone. Five hundred Somalis are now arriving at this bleak Kenyan outpost every day. They join a population of 267,000 and counting, in a facility built to shelter just 45,000. While the world has been captivated by the high seas drama of Somalia's pirates, this human tide has swollen the ranks of Dadaab, turning it into the world's largest refugee camp.

The new arrivals sit in their hundreds under a makeshift tarpaulin, trying to keep perfectly still in temperatures that reach 40C in the shade. It speaks volumes for the horrors unfolding in Somalia that people will abandon their homes, risk arbitrary arrest, death or starvation to reach the desolate welcome on offer in this corner of northern Kenya.

These people are proof of the human cost of the accelerating collapse of Somalia, yet their fate attracts nothing like the global interest that surrounds Somali piracy and its threat to commerce. The UN refugee agency (UNHCR) that runs Dadaab urgently needs new money from international donors and new land from the Kenyan government. Neither has been forthcoming.

The annual budget for this camp is $33m - roughly half the annual operational cost of a single warship patrolling the Indian Ocean in search of modern-day Blackbeards.

The story of Dadaab is in some senses the story of modern Somalia. Its three camps, Hagadera, Ifo and Dagahaley, were built to house those who fled when the last functioning central government - that of socialist dictator Siad Barre - collapsed in 1991. The camps soon reached their initial capacity and as the mother country just 50 miles to the north has sunk deeper and deeper, so the number of refugees has risen and risen. An entire generation of children has grown up knowing Dadaab as their only home. There have been 14 failed governments since then, Somalia is in a state of anarchy and Dadaab is facing an extraordinary influx. Last August the land ran out and the UN had to declare the camps full. It has not stopped the desperate masses arriving.

Somalia is a country surrounded by political walls. Its land borders with Ethiopia and Kenya have been closed to protect their countries from the Islamic militias on the other side. In reality the only effect of the closures has been to make it even harder for people like Osman Hussein Bare to flee. With his family seated in a tired circle around him, the middle-aged man stands to tell his story with some dignity. "There is war in Somalia," he explains. "A lot of bullets; day and night they are fighting in the place."

A farmer from a village close to the coastal city of Kismayo, Mr Bare found his life taken over by the emergence of the powerful Al-Shabaab militia. The breaking point, which sent him trekking for two nights across a sealed border to another country, came when the militants began to dig up the remains of religious leaders from Islamic sects they considered their rivals. "The way they rule I cannot live under them," he said.