US Secretary of State Colin Powell called atrocities in Sudan's Darfur region genocide and demanded a UN probe into the crisis, hastening moves toward sanctions on Khartoum.
Powell told a Senate hearing that evidence compiled by the United States "concluded that genocide has been committed in Darfur and the government of Sudan and the Janjaweed bear responsibility, and that genocide may still be occurring."
The Sudanese government has been accused of arming and backing Arab militias, known as Janjaweed, which have rampaged through the western Darfur region.
An estimated 50,000 people have been killed and 1.4 million more uprooted in a campaign against black Africans, which began in February 2003 as an attempt to crush a rebel uprising.
"The United States is appalled by the violence in Darfur, Sudan," President George W. Bush said later, reiterating his administration's finding that genocide had been committed.
Powell said the United States had proposed a resolution to the UN Security Council, asking for a "full-blown and unfettered" investigation to confirm genocide had been committed and possibly consider oil sanctions on Sudan.
He said "the threat of sanctions is still out there, over them, particularly on the sector that is of greatest concern to them."
Powell admitted an "overall reluctance" by the international community to impose sanctions amid worry they might fail, but said the European Union would back the United States.
But the 15-nation UN Security Council emerged divided over the proposed US resolution.
Russia, Pakistan and especially China voiced strong objections to the draft, which hangs the threat of sanctions over Sudan, diplomats who attended the session said.
The resolution, like a similar measure passed July 30, demands that Khartoum disarm and rein in the Janjaweed and take other steps to end the violence or face international sanctions.
Sudan's foreign minister rejected US charges of genocide in Darfur as a reelection ploy by US President George W. Bush.
Sudan said it "categorically rejects" US accusations that it carried out genocide in the western region of Darfur, Khartoum's ambassador to Washington was quoted as saying in a letter published by the press in Sudan.
"To consider what is happening in Darfur as genocide does not represent the international concensus and sends a negative signal to the other side who are negotiating with the government."
In Nairobi, Sudan's deputy parliamentary speaker Angelo Beda said Western powers were "playing with the word genocide" as a pretext to "come in with occupying forces for the sake of oil."
Sudan produces around 250,000 barrels a day of oil, and the government recently announced proven deposits in Darfur.
But a spokesman for the rebel Sudan Liberation Movement, Abdelhafiz Mustafa Musa, called the US move "a welcome development," saying the Sudanese government and the Janjaweed "continued to kill innocent civilians."
The proposed US resolution would call Khartoum to cooperate fully with an expanded African Union (AU) force and for cessation of Sudanese military flights over the Darfur region.
The resolution also provides for international overflights to monitor Darfur.
Sudan has approved the international genocide convention and is obliged under it to prevent and punish acts of genocide.
"To us, at this time, it appears that Sudan has failed to do so," Powell said.
A key provision of the genocide convention provides that contracting parties "may call upon the competent organs of the United Nations" to take action to prevent and suppress acts of genocide.
Powell said US evidence from interviews on refugees and other sources showed that the "Janjaweed and Sudanese military forces have committed large-scale acts of violence, including murders, rape and physical assaults on non-Arab individuals."
He said they had destroyed villages and foodstuffs and obstructed humanitarian aid from reaching affected populations, thereby leading to further deaths and suffering.
"Despite having been put on notice multiple times, Khartoum has failed to stop the violence," he told the Senate Foreign Relations Committee.
The panel's chairman Dick Lugar introduced legislation that would provide an additional 300 million dollars in fiscal year 2005 aid to relieve the Sudan humanitarian crisis.
It would add to the nearly 600 million dollars already targeted for Sudan in during that period, Lugar said.
Powell said that the AU force was the "number-one priority" for the United States, adding that 25 million dollars had been earmarked for an expanded force, the mandate of which was the subject of Nigerian-sponsored talks between Sudan and Darfur rebels.
NATO Secretary General Jaap de Hoop Scheffer said in Helsinki that the alliance could work together with the EU to provide logistical support to the AU, which has several hundred troops in Darfur monitoring a shaky ceasefire.
Powell stressed that global action was critical.
"Call it a civil war. Call it ethnic cleansing. Call it genocide. Call it none of the above. The reality is the same: There are people in Darfur who desperately need our help," he said.