The U.N. Security Council on Friday adopted a resolution threatening to consider sanctions against Sudan if it fails within 30 days to apprehend and prosecute Arab militias accused of killing tens of thousands of black Africans in Darfur, Sudan.

The U.S.-sponsored resolution passed by a vote of 13 to 0, with China and Pakistan abstaining on grounds that it would undermine U.N. efforts to secure Sudan's cooperation in resolving the crisis. But supporters of the resolution said that Khartoum would put an end to the killing in Darfur only if it is faced with a credible threat of action.

The three-page resolution is part of a broader council effort to maintain pressure on Khartoum to comply with a July 3 agreement with the United Nations to crack down on the militia, known as the Janjaweed, and to provide greater access to humanitarian relief workers. Relief agencies are trying to prevent the deaths of hundreds of thousands of people from hunger and disease as the region enters the height of the rainy season.

"The resolution, in stern and unambiguous terms, puts the government of Sudan on notice that it must fulfill the commitments it made," said John C. Danforth, the U.S. ambassador to the United Nations. "Sudan must know that serious measures -- international sanctions -- are looming, if the government refuses to do so."

Danforth cited U.N. estimates that as many as 440 are dying in Darfur each day as a result of the ongoing crisis, noting that more than 11,000 people may have died since Sudan signed its agreement with the United Nations. U.S. officials say the government-backed militias, meanwhile, continue to murder, rape and terrorize civilians in camps throughout Darfur.

After the vote, Sudan's U.N. envoy, Elfatih Mohamed Erwa, insisted that his government is trying to rein in the armed militias, citing the recent arrest of militia members, but said Sudan needs more time to resolve the crisis. He criticized the council, saying it singled out Sudan while declining to condemn American prison abuses in Iraq and Afghanistan or Israeli treatment of Palestinian civilians. "What I'm seeing is a policy of unfairness, a policy of injustice, a policy of double standards," Erwa said in a lengthy address to the council.

The crisis in Darfur has presented the council with one of its most serious humanitarian challenges in Africa since 1994, when it failed to intervene in Rwanda to halt genocide.

Human rights advocates and other critics of the council said Friday's action was too weak to force the Sudanese government to reverse the worsening humanitarian calamity.

"Giving Khartoum another 30 days as the current resolution does before any specific action is even considered literally condemns thousands more Sudanese to death," said John Prendergast, an expert on Sudan at the International Crisis Group.

Danforth said that "many people who are concerned about Darfur would say that this resolution does not go far enough. Last week, the Congress of the United States passed resolutions referring to atrocities in Darfur as genocide. Many people would want us to do the same. Perhaps they are right. But it is important that we not become bogged down over words. It is essential that the Security Council act quickly, decisively and with unity. We need to fix this humanitarian problem now."

For now, the Bush administration has ruled out U.S. military intervention in Sudan to stop the violence. But it has encouraged Sudan to ask a small contingent of African Union monitors to expand their mandate to include the securing of humanitarian relief corridors. "The best way out of this is to . . . turn to the African Union and say, 'Okay, come on in,' " said a senior State Department official who briefed reporters on the condition he not be named.

The Darfur crisis began in February 2003, when two rebel groups, the Sudan Liberation Army and the Justice and Equality Movement, took up arms against the government, citing discrimination against the region's black tribes, primarily the Fur, Masalit and Zaghawa. Khartoum organized the region's Arab tribes into armed militias and supported them with airpower as they launched a military campaign that has led to the deaths of 30,000 to 50,000 people, according to U.S. officials and human rights activists.

The resolution adopted Friday imposes an arms embargo on Darfur and "demands" that the Sudanese government "disarm the Janjaweed militias and apprehend and bring to justice Janjaweed leaders and their associates."

The council also "expresses its intention to consider further actions" -- including economic and diplomatic sanctions -- if Sudan fails to clamp down on the armed militias and improve aid workers' access to Darfur. Another vote by the council, however, would be required before sanctions or other measures could be imposed.

Such measures could include freezing Sudanese government bank accounts, restricting the travel of Sudanese leaders abroad and banning outside companies from doing business in the country, dealing a blow to the oil industry, according to the State Department official. "We've got the Sudanese government's attention now," he said.

The United States would consider there to be sufficient progress to avoid sanctions if the killing by militia members subsides and there is a doubling of aid workers' access to refugee camps over the next month, the official said. "Then we'd be into an argument about how this is a pathetic relief operation, as opposed to a huge tragedy," the official said.

Lee reported from Washington.

Sudan's U.N. Ambassador, Elfatih Mohamed Erwa, listens to speakers in the Security Council after it voted to give Sudan 30 days to disarm militias blamed for killing thousands.