UN chief Kofi Annan has urged the Security Council to reinforce Darfur's African Union (AU) peacekeepers, while pressuring Sudan to accept a UN force.
The African Union's mission in Sudan is short of funds
Mr Annan gave three options for the UN, with Sudan's approval, to bring peace.
One scheme would involve 18,600 African and Asian troops, making it the world's largest UN peace force.
But Sudanese President Omar el-Bashir has vowed to never allow a UN force into Darfur. The UN cannot assume a role without the government's consent.
"Securing the consent of the government of Sudan will require continued intensive discussions with Khartoum by council members, by key member states and regional organisations, as well as by the United Nations," Mr Annan said.
"No effort should be spared to send the simple, powerful message: International involvement will increase the chances of peace taking root in Darfur, will strengthen the credibility of the peace process and the protection of the suffering populations of Darfur," he said.
He warned that the window of opportunity created by the Darfur peace agreement signed in May would be lost if there was no extra effort to implement it on the ground.
The current AU peacekeeping force in Sudan's war-torn west is 7,000-strong.
Some 2m people have fled their homes in Darfur since conflict began in 2003, and tens of thousands of people are reported to have been killed in ongoing violence.