Sudanese rebels cautiously welcomed U.S.-backed proposals to salvage a peace agreement for Darfur Thursday and the international community urged them to finally accept the deal aimed at resolving a crisis that has cost at least 180,000 lives.

Four pages of last-ditch revisions to the 85-page peace plan drawn up by African Union mediators offered concessions to the rebels on integrating fighters into the Sudan armed forces, compensation for war victims and power-sharing.

They were presented to the warring parties Thursday afternoon, hours before a deadline to reach agreement, already extended twice since Sunday.

That deadline passed at midnight Thursday but the negotiators were continuing to meet two hours past the time limit. They did not explain the time extension to reporters.

Rebel negotiators, who rejected the initial deal but faced intense pressure from the European Union, Britain and the United States to compromise, were optimistic.

"We are going to study them, but the improvements give us the sign that we can agree, that we do not need to renegotiate and that there will be no further delay for the final agreement," Jaffer Monro of the largest rebel group, the Sudan Liberation Movement, told The Associated Press.

The Sudanese government agreed to the initial proposal and has shown increasing flexibility since the United States and Britain sent top envoys to join the talks in Nigeria's capital. A spokesman indicated Wednesday that it could accept the U.S.-drafted changes as well.

"We hope that the Americans' suggestion will be agreed upon," Sudanese government spokesman Abdulrahman Zuma told AP.

With patience and time running out, the European Union and Britain put the onus on the rebels and African leaders in the Nigerian capital of Abuja for a health conference planned to hold a mini-summit with all sides Thursday evening to add to the pressure to overcome the impasse after two years of staggered negotiations.

The European Union called on the rebels to come to a "definitive agreement," and said failure would be "irresponsible considering the enormous human suffering."

British Foreign Affairs Minister Ian Pearson warned: "The international community will not understand if they (the rebels) fail to take this opportunity to bring peace to Darfur and security to its people."

African leaders in Abuja for a health conference were scheduled to meet with warring parties Thursday evening, to add pressure to resolve the issue.

Decades of low-level tribal clashes over land and water in Darfur, a vast region about the size of France, erupted into large-scale violence in early 2003 with rebels demanding regional autonomy. The central government is accused of responding by unleashing Janjaweed militias upon civilians, a charge Sudan denies.

At least 180,000 people have been killed and more than 2 million forced to flee their homes in what the United Nations has called the world's worst humanitarian crisis. The conflict also has spilled into Chad and the Central African Republic.

Revisions to the peace plan made available to AP called for 4,000 rebels to be integrated into Sudan's armed forces and another 1,000 into the police force. In addition, 3,000 rebels would be given training and education at military colleges. The initial proposal mentioned no figures.

The new deal also would provide for rebels to comprise 33 percent of all newly integrated battalions nationwide, and 50 percent in areas to be agreed, notably Darfur.

Zuma said Wednesday his government had considered integrating no more than 100 rebels into the armed forces, and he expected a final agreement to rest somewhere between that figure and the proposed 4,000.

"Through this so-called American initiative, it seems that the government is going to make some concessions, especially about reintegration and disarmament," he said.

The disarmament refers to the Janjaweed Arab militia that is accused of some of the worst atrocities in Darfur. Zuma said Khartoum was willing to agree to the new proposal for a speedy disarmament. The initial proposal was for them to be confined to barracks for an unspecified transitional period.

Other significant changes included giving the rebels 70 percent of all legislators' seats in the three Darfurian provinces. It would be a major concession from Sudan's government but still does not meet rebel demands for the position of second vice president in the central government instead of the proposed special adviser to the president, which would be the No. 4 instead of No. 3 position in the Khartoum government hierarchy.

Rebel negotiators said they remained concerned about security arrangements. The agreement calls for a protection force for civilians but does not detail its composition. They want a joint protection force including rebels and government, African Union and U.N. forces.

The envoys, U.S. Deputy Secretary of State Robert Zoellick and Britain's Cooperation Minister Hilary Benn, were not immediately available for comment.