The United Nations Security Council has unanimously passed a resolution giving Sudan's government one week to allow an assessment team into the troubled Darfur region.
The team would prepare for the U.N. to take over an African Union-led peacekeeping mission that is currently in Darfur.
The U.S. Ambassador to the United Nations, John Bolton, says the resolution is key to speedy action in Darfur.
The resolution also threatens "strong and effective measures" against anyone who stands in the way of the Darfur peace accord, signed this month by Sudan's government and the largest rebel group, the Sudanese Liberation Movement.
Sudan has giving conflicting signals about whether it will allow the United Nations to take over the peace keeping mission. But the African Union agreed Monday to hand the force over as early as September.
Meanwhile, the United Nations refugee agency said Tuesday that Darfur rebel groups are continuing to forcibly recruit refugees who have fled to eastern Chad.
More than 200,000 Sudanese have fled to eastern Chad from the violence-plagued Darfur region.
Three years of fighting in Darfur between rebel groups and government backed militias has left an estimated 180,000 people dead and millions of other displaced.
Two rebel groups have not signed the Darfur peace accord - the Justice and Equality Movement and a faction of the SLM. The AU has given them until the end of the month to sign or face the threat of international sanctions.
Some information for this report was provided by AFP, AP and Reuters.