The United Nations has said it is "extraordinarily concerned" about the situation in Sudan's Darfur region.
The Darfur conflict has displaced millions of people
Discussions have been taking place at the UN in New York about sending a major peacekeeping force there.
UN Deputy Secretary-General Mark Malloch Brown said "something very ugly was brewing" and the humanitarian and security situation was deteriorating.
Britain and the US have introduced a UN draft resolution authorising deployment of at least 17,000 UN peacekeepers.
With the attention of the world focused on the situation in Lebanon, UN officials are anxious not to lose sight of the on-going violence in Darfur, the BBC's Mike Sergeant reports from the UN in New York.
Sudan's government and the pro-government Arab militias are accused of war crimes against the region's black African population, although the UN has stopped short of calling it genocide.
More than 2m Sudanese have fled their homes and tens of thousands have been killed in the three-year conflict.
The new troops would reinforce an African Union presence already there.
"We are extremely worried about the deterioration in the humanitarian and security situation in Darfur and the absence of a clear political path to the deployment of the UN force," Mr Malloch Brown said.
US state department spokesman Tom Casey said the Sudanese government had both a need and an obligation to accept a UN force.
The British officials who drew up the resolution say they hope it can be adopted by the Security Council within a month, to enable troops to be deployed in January.
But there are big problems, our correspondent says.
Sudanese President Omar al-Bashir has said he does not want UN troops in Sudan.
Russia and China have some reservations and there is the question of who would supply troops, with UN peacekeeping operations looking increasingly stretched, our correspondent in New York notes.