The Bush administration for the first time on Thursday called attacks in Sudan's (search) Darfur region by government-backed Arab militia against black Africans "genocide."

The designation by Secretary of State Colin Powell (search) came as a U.S. proposal in the U.N. Security Council to impose sanctions against Sudan encountered opposition. Powell told Congress that Sudan's government is to blame for the killing of tens of thousands and uprooting of 1.2 million people.

In recent interviews with 1,136 refugees in neighboring Chad, the State Department found a "consistent and widespread pattern of atrocities committed against non-Arab villagers," according to a department report. It added that about a third of the refugees who were interviewed heard racial epithets while under attack.

Powell said that as a member of the 1948 international genocide convention, Sudan is obliged to prevent and punish acts of genocide.

"To us, at this time, it appears that Sudan has failed to do so," he said.

Powell's announcement came as the United States was pressuring the U.N. Security Council to impose sanctions on Sudan's oil industry, among other measures, if the government does not take steps to improve security in Darfur (search).

Such sanctions are opposed by China and Pakistan, Security Council members that import Sudanese oil.

The Bush administration has not seriously considered sending troops to Sudan. The African Union, a continent-wide security group, has dispatched 125 monitors to Darfur who are protected by 300 African Union troops.

U.N. envoy Jan Pronk urged Sudan last week to allow more than 3,000 troops into the region to stop violence and to prevent the conflict from escalating.

In Abuja, Nigeria, where Darfur peace talks are under way, Sudanese Deputy Foreign Minister Najeeb El-Khair Abdel Wahab criticized Powell's action.

"We don't think this kind of attitude can help the situation in Darfur. We expect the international community to assist the process that is taking place in Abuja, and not put oil on the fire," he said.

The European Union also was critical. "We have not discussed specifically the use of the word genocide," said spokesman Jean-Charles Ellermann-Kingombe. "For us, we have noted that there is an extremely serious situation that still requires a huge humanitarian aid effort."

State Department officials acknowledged the possibility that the genocide designation could hinder U.S. efforts to encourage more robust Sudanese government efforts to protect Darfur's citizens. And Powell has acknowledged the designation will not lead directly to any material benefit for Darfur's victims.

The 1948 genocide convention defines that act as a calculated effort to destroy a national, ethnic, racial or religious group in whole or in part.

State Department officials could not say whether any convention member had ever invoked the accord. U.N. spokesman Fred Eckhard said he believes Powell's designation was a first.

Other crises that often carry the genocide label have occurred in Rwanda in 1994 and Cambodia from 1975-79. Former Yugoslav President Slobodan Milosevic is facing genocide charges before an international war crimes tribunal at The Hague.

Congress this summer called the violence in Sudan genocide.

Under the genocide convention, the United Nations can take any action under its charter that it considers "appropriate for the prevention and suppression of acts of genocide," Powell said. He urged the U.N. Security Council to approve a resolution that asks the United Nations to look into "all violations of international humanitarian law and human rights that have occurred in Darfur."

The violence in Darfur began when black African tribes rebelled in February 2003, accusing the national government in Khartoum of neglecting their interests. In response, Powell said, Arab militias coupled with Sudanese military forces "committed large-scale acts of violence, including murders, rape and physical assaults on non-Arab individuals."

Senate Majority Leader Bill Frist, R-Tenn., who has visited Sudan repeatedly, said the crisis "could be one of the greatest humanitarian tragedies of all time."

Democratic presidential candidate John Kerry said Thursday, "The United States should ensure the immediate deployment of an effective international force to disarm militia and facilitate the delivery of humanitarian assistance in Darfur."

In a speech to the National Baptist Convention in New Orleans, Kerry said, "The Sudanese government has thus far rejected such force, but the United States should lead the United Nations, truly lead, in order to make plain that we're not going to accept Khartoum continuing to block its deployment." His remarks got a standing ovation.

In a separate statement issued hours after Kerry's remarks, President Bush highlighted American efforts to ease the suffering in Darfur.

"We have provided more than $211 million in aid and humanitarian relief, and we will provide an additional $250 million," Bush said.

He also said neither the militias nor the rebels have respected a cease-fire agreement signed last spring.

"It is clear that only outside action can stop the killing," Bush said. "My government is seeking a new Security Council resolution to authorize an expanded African Union security force to prevent further bloodshed. We will also seek to ban flights by Sudanese military aircraft in Darfur."

The Darfur crisis has attracted the interest of many conservative Christian groups and civil rights organizations.

For example, Samaritan's Purse, a Christian relief organization, has provided food, medicine and other supplies to thousands of displaced families there, and evangelicals have joined with moderate religious groups to increase public awareness about the suffering.

On the civil rights front, the Rev. Jesse Jackson recently visited and has called for vastly increased U.S. humanitarian relief efforts in Darfur.