Secretary of State Colin L. Powell said for the first time that genocide has taken place in Sudan and that the government in Khartoum and government-sponsored Arab militias known as Janjaweed "bear responsibility" for rapes, killings and other abuses that have left 1.2 million black Africans homeless.

Powell's long-awaited declaration -- the result of months of investigation and discussion within the State Department -- is intended to increase pressure on the Sudanese government to end the violence in Sudan's Darfur region. But refugee organizations and aid groups said it also will make it much harder for the Bush administration to step away from the problem if its diplomatic efforts are unsuccessful.

Powell's statement before the Senate Foreign Relations Committee came as the United States began negotiations at the United Nations on a Security Council resolution that threatens to consider new sanctions against Sudan if it fails to crack down on the militias, and calls for the establishment of a U.N. commission of inquiry to determine whether Sudan and the militia are responsible for genocide. A finding of genocide does not impose obligations on the United States; but as a signatory to the 1948 Genocide Convention, the United States is committed to preventing and punishing genocide.

Sudanese officials reacted angrily to Powell's announcement, saying it will only make it more difficult to resolve what they describe as an internal problem. At the United Nations, officials from a number of Security Council member nations expressed concern that Powell's statement might complicate efforts to win broad support for a new resolution. Both the African Union and the Arab League have already said there is no genocide, while the European Union said it does not have enough information.

-- Glenn Kessler

and Colum Lynch

Secretary of State Colin L. Powell says Khartoum bears responsibility for Darfur killings.