They warned another 2.5 million people faced famine and said the humanitarian crisis had reached an ''unimaginable and extraordinary level of tragedy".

The United Nations and the Security Council have largely stayed out of the political aspects of the war, focusing mainly on humanitarian relief.

The SPLA has extended its ceasefire in the south west

But Care International, Oxfam, Medecins Sans Frontiers and Save the Children told the council that aid was not enough.

"Sudan's warring factions use civilians as human shields and as strategic military resources," the agencies said.

They called on the UN to "generate a forceful and positive lobby for peace" that would include shuttle diplomacy, followed by summit level meetings and a full time special representative for UN Secretary General Kofi Annan in the area.

"Humanitarian assistance alone, in a political vacuum, will not solve Sudan's problems nor stop the next famine. What we need is the political will to end the war," said Guy Tousignant, secretary general of Care International.

Oxfam's British director, Dr David Bryer, said Sudanese society was so weakened that further humanitarian disasters were inevitable.

Call to extend ceasefire

Sudan's 15-year war, one of the longest conflicts in Africa, pits the mainly Moslem, Arabic north against rebels who want autonomy for the mainly Christian and animist south.

The government and the rebel Sudan People's Liberation Army (SPLA) recently extended a ceasefire until mid-January in the Bahr el-Ghazal area.

But the agencies said it should be broadened throughout southern Sudan or it might only allow warring parties to use their troops for fighting elsewhere.

Currently the only forum to bring the two main combatants together is the regional Inter-Governmental Authority on Development, known as Igad, which meets infrequently in Ethiopia.