Sixteen aid agencies say they face new challenges in Somalia, after the al Shabab militant group banned their activities in the southern and central parts of the country. Al Shabab accuses the agencies of bias and misconduct.

One of the organizations affected by the ban is the U.N. refugee agency, UNHCR.

"Like a lot of the other agencies, we're assessing the situation both in terms of implications on the ground and the implications for our operations," said Andy Needham, spokesman for the Somalia office.

Bad to worse?

This year southern and central Somalia were hit hard by drought and famine, along with conflict. Now, there's another problem.

"There have been heavy rains of late, which is I guess ironic for maybe some people to comprehend in the wake of all this talk about drought and famine. But these are seasonal rains. So what this has done is it has compounded the difficulties for the IDPs living in settlements, for example, in Mogadishu. So what we've actually seen is that we have entire settlements, where people are in tents and shelters, have been kind of washed out. And the heavy rains are flowing through the places where people are living," he said.

And Needham says there's not much that can be done about it.

"Because they're living cheek by jowl, so close that it's impossible even to dig channels so that the water can get out. So there have been pretty miserable conditions when the rains come. When the temperature drops and the rains come, we saw in previous years that that had a bad effect in terms of increased numbers of deaths through hypothermia, especially among children," said Needham.

Can't get there

Even before al Shabab banned many aid groups, the rains had already brought their humanitarian efforts to a standstill. Many roads are impassable in southern and central Somalia.

"What we're hearing from people on the ground is that some certain towns and villages are actually effectively completely cut off for food deliveries. And even people, if they have means, if they have some small amounts of money, they actually can't buy anything because people cannot travel to these towns because of the roads and perhaps fear of being caught up in some sort of ongoing clash," he said.

Al Shabab has allowed some aid groups to remain, namely Doctors Without Borders and the International Committee of the Red Cross.

In neighboring Kenya, insecurity continues to disrupt UNHCR operations at the Dadaab refugee camp. Hundreds of thousands of Somalis find shelter there. However, the insecurity has brought a halt to the registration and health check of new arrivals.

And in Ethiopia, at the Dollo Ado refugee camps, the U.N. agency reports high rates of severe acute malnutrition among children under age five.