The UN secretary-general has urged Security Council members to take immediate action over a US draft resolution on Sudan's Darfur region.
The UN has appealed for millions more dollars in aid
Kofi Annan said civilians were being attacked "even as we speak" despite Khartoum's pledge to stop the violence.
He was speaking as council members debated a new draft of the resolution.
The US says it would like a vote to be taken by Saturday, but some members, including China which has a veto, have opposed the threat of sanctions.
The new resolution under discussion calls for an enlarged African Union (AU) monitoring force in Darfur.
It also asks Mr Annan to set up an international commission to investigate whether human rights violations in the region amount to genocide.
And it threatens the Sudanese government with measures such as oil sanctions if it does not disarm the Janjaweed militia and protect civilians.
"I have urged the Security Council to act on the draft resolution without delay, and to be united as possible in the face of the crisis," said Mr Annan.
"It is urgent to act now. Civilians are still being
attacked and fleeing their villages as we speak," he told reporters.
He said the international community must put pressure on both the Sudanese government and the rebels to come to a political agreement and end the fighting.
US DRAFT RESOLUTION
Enlarged African Union (AU) monitoring force
UN to investigate claims of genocide
Threatens Sudan with oil sanctions if it does not disarm the militias and protect civilians
Sudan to submit the names of militiamen and others arrested for human rights abuses
All Sudanese parties to stop human rights violations
US ambassador to the UN, John Danforth, said "time is of the essence" adding that he hoped the vote would be taken by Saturday afternoon.
China's UN ambassador, Wang Guangya, said he "still had some difficulties" with the text but would not be drawn on whether he would use the veto.
"I think actually we need a resolution that will be helpful for a solution, not a resolution that will make matters worse," he said.
Sudan has called earlier drafts of the resolution "imbalanced and unfair".
More than a million have fled their homes in western Sudan since February.
Some 10,000 people are dying from disease and conflict every month, according to the World Health Organisation.
More than 1m displaced
Up to 50,000 killed
More at risk from disease and starvation
Arab militias accused of ethnic cleansing
Sudan blames rebels for starting conflict
Meanwhile, peace talks between the government and rebels in the Nigerian capital, Abuja, have been postponed for at least three weeks.
One rebel group, the Justice and Equality Movement, refused to sign a humanitarian accord and declared the talks had collapsed.
The other major group, the Sudan Liberation Army, said it would wait until Friday before making its final decision.
The talks are deadlocked over whether rebels should disarm at the same time as the pro-government Janjaweed militias.
The government says the rebels started the conflict so they should disarm at the same time.
But the rebels accuse the Janjaweed of widespread atrocities, and say they militias must lay down their weapons first.
The government denies backing the Janjaweed.
The rebellion began last February, when two groups took up arms, accusing the government of ignoring Darfur.
Many of Darfur's nomadic Arab groups backed the government against the rebels, dominated by black African farmers.