KABUL, Afghanistan - Afghanistan's security situation has overshadowed the glaring humanitarian needs of the nation's poorest, and their plight may worsen as international assistance wanes, a top UN official said Wednesday.

Economic hardship could be an unwanted byproduct of the handover of security responsibilities to Afghan forces, as the U.S.-led military coalition prepares to pull out its foreign combat troops by the end of 2014. The transition will likely coincide with a decline in foreign aid that could lead to critical economic problems as related jobs dry up, according to a World Bank report released this week.

The report said up to 10 per cent of the work force has benefited from aid-financed jobs, most short-term. As aid decreases, unemployment and underemployment are expected to rise. It said the impact would be felt most in conflict areas and cities.

That could result in more economic migrants flooding makeshift camps, especially in urban centres. Those are already filled with people displaced by fighting or returning from refuge abroad, said Valerie Amos, the UN's humanitarian affairs chief and emergency relief co-ordinator.

"The transition over the next couple of years will result in a lot of people losing work," she said, describing it as a huge challenge for the international community, the government and aid groups.

At the camp that Amos visited in Parwan-i Se, near central Kabul, people live in small mud huts with roofs made of wooden poles, plastic bags and sheeting. Cows stand tied in front of rickety homes, and the smell of waste, both animal and human, fills the air. Children play in piles of garbage.

"The situation as we can all see here is deeply, deeply distressing," Amos said. "Expecting people to keep on living in these kinds of conditions is simply not acceptable."

Abdul Samad, a camp elder, said the people there were both economic and conflict refugees. He said most of the 110 families were from Surobi, a dangerous district in eastern Kabul province that sees regular insurgent attacks and kidnappings.

He said back home they find themselves caught between the government and the Taliban, and each accuse them of helping the other.

The only real employment in the camp is pushing hand carts through the streets, selling goods.

This past winter, eight children in the camp died of pneumonia or other illnesses in the harsh, freezing weather, Samad said. During heavy rain, water rushes through the camp, carrying waste from its open sewers.

He said he has applied for housing with the government, but it can often take five years or more for applications to be processed. He faces several more years living in the camp -- if he is allowed to stay. The land is privately owned, and everyone living there has been told to leave.

Amos said migrants "don't necessarily have anywhere to go, and they are drawn to Kabul as the capital city." Amos said with unemployment already high in Kabul, a new influx of people would only lead such shantytowns to grow.

Up to 35,000 internally displaced people are already living in temporary camps in Kabul, Amnesty International said in a report in February. Nationwide, displacements are on the rise. An estimated 91,000 people fled their homes because of conflict in the first six months of 2011 -- up 46 per cent from the 42,000 displaced in the first half of 2010, as fighting has spread to areas of the country that had been relatively peaceful.

The UN estimates there are 500,000 internally displaced people across the country.

The focus on security has in some ways hindered aid groups, Amos said.

"I think the humanitarian issues do get overlooked, partly because security has made our ability to move around difficult in some areas," she said. On the other hand, she noted that if the resources that have gone into security increase stability, that could allow greater access to people in need.