Martin Dawes: the needy are being pushed aside...

As the United Nations and aid organisations struggle to prevent widespread starvation across southern Sudan, the relief effort in the upper Nile region is being gutted.

The militia have burnt down a hospital and feeding centre

A humanitarian cease-fire in the country's long-running civil war is not being honoured by two rival pro-government factions.

The town of Leer was taken days ago, but a vindictive act is being played out. The militia that took control at the end of last week has razed to the ground every aid building, including a hospital and a feeding centre.

A woman watches while her house is burnt to the ground

It is blatantly obvious that compounds of aid agencies were the first buildings to be destroyed.

There is no sign in Leer of the UN food stocks that were sent in for 18,000 people. Most of the population has fled. Those who were too sick stayed put and are surviving on wild fruits.

Musa Bungudu of the UN's Operation Lifeline Sudan said that the relief effort in the upper Nile had been crushed.

The sick and starving have nowhere to go

"We are back to square one because the feeding centre that has been established, the TB centre that has been established ... all that has been established is back to zero," he said.

While cease-fires are giving some hope in a desperate situation, a firestorm of faction fighting is pushing aside the needy, the aid-workers - perhaps even humanity itself.

Well armed and competent, the militia's leader has split from the main ally of the government in Southern Sudan.

The declared cease-fire means nothing to the fighting factions

The militia commander who took the town blamed the government's main southern ally Riek Machar for starting the fighting. He said the aid-workers could come back if he gets authorisation from his leader.

Armed by a government that talks of cease-fire, the fighters say they will continue the fight against the allies of that same regime.