Washington ? In a new signal of its concern over the humanitarian crisis in Sudan, the Bush administration Thursday declared for the first time that the African country’s troops and allied militias have committed genocide.

Secretary of State Colin L. Powell told senators that a State Department report drawn from interviews with 1,000 Sudanese refugees had concluded there was a “consistent and widespread pattern of atrocities committed against non-Arab villagers” in the Darfur region.

Speaking before the Senate Foreign Relations Committee, Powell said that the government and militia, known as “janjaweed,” “bear responsibility” for the atrocities and that “genocide may still be occurring.”

Human rights groups have been pressing for such a declaration, hoping to increase international pressure to resolve what is considered the world’s worst ongoing humanitarian crisis. The United Nations estimates 50,000 blacks have died and 1.2 million have been displaced as government and allied fighters have attacked village after village in Darfur since a rebellion erupted there in April 2003.

But views differed on whether the new U.S. stand would provide momentum for a solution, since many nations oppose international intervention. At the United Nations, some diplomats even predicted a backlash.

“It will make a difference,” said Pakistani Ambassador Munir Akram, who opposes intervention. “It is bound to make things more difficult.”

Powell played down the possibility that the new American position would make much of a difference in diplomatic efforts, even though some people “seem to have been waiting for this determination of genocide” in order to take action.