US President George W Bush has signed into law legislation that enables him to impose sanctions on Sudan, in protest at the violence in Darfur.
Thousands have died in Darfur in recent months
Measures include a travel ban on Sudanese leaders and the freezing of officials' and companies' assets.
The new law calls on the president to encourage other United Nations members to implement similar sanctions.
The United States has already declared the attacks in Darfur, where some 70,000 have died, to be genocide.
It blames pro-government Arab militia - known as the Janjaweed - for much of the fighting which has forced some 1.8 million people from their homes in what the UN terms as one of the world's worst humanitarian crises.
Khartoum has denied allegations it is backing the Janjaweed.
Correspondents say it is not yet clear what action Mr Bush will take, as the law in not binding.
Earlier this week, UN Secretary General Kofi Annan said current attempts to end the two-year-old conflict between the rebels, the army and the militia groups were not working.
He said the UN Security Council need to find new ways to resolve the crisis.
There are two existing UN resolutions threatening possible sanctions against the Sudanese authorities.
But China and Russia, which have a veto on the council, oppose sanctions.
The new US bill also authorises $300 million in aid - including help to deploy more African Union (AU) troops to Darfur.
The force currently stands at less than a quarter of the projected number of 4,000 troops.
Security on the ground continues to deteriorate and the AU troops in Darfur - to protect the ceasefire monitors - are having little impact on the fighting.
UK charity Save the Children announced on Tuesday it was pulling out of the region after four of its staff died in attacks.
The aid agency Medecins Sans Frontieres has said five out of 29 of its workers who went missing during an attack on Labado last week have been found, the French news agency AFP reports.