WASHINGTON – The Bush administration has settled on the idea of sending up to several hundred NATO advisers to help bolster African Union peacekeeping troops in their efforts to shield villagers in Sudan’s Darfur region from fighting between government-backed Arab militias and rebel groups, administration officials said.

The move would include some American troops and mark a significant expansion of American and allied involvement in the conflict. So far, NATO’s role has been limited to airlifting African Union forces to the region and providing a few military specialists to help the peacekeeping contingent.

The proposal, which faces uncertain approval within NATO because of concerns that it could be a distraction from operations in Afghanistan, falls well short of more aggressive measures that some have advocated, such as sending ground combat troops or providing air patrols to protect peacekeepers and prevent the bombing of villages. These options have been ruled out as unnecessary at this time, an administration official said.

In general, American officials said, their aim has been to address shortcomings in the African Union force without upstaging that force and stirring resentment in a region highly sensitive to the presence of Western troops.

Plans under consideration envision fewer than 500 NATO advisers. They would be assigned to African Union headquarters units and assist in logistics, communications, intelligence, and command and control activities, not engage directly in field operations. The likely number of American advisers has yet to be determined, officials said.

“This is supposed to be a support effort, not a take-over-the-mission effort,” said the administration official, whose name and agency could not be identified under terms of the interview. As the reason for insisting on anonymity, the official cited the sensitivity of the internal planning.

The proposed deployment is intended as an interim measure until a U.N. force – larger and with a broader mandate than the African Union force – can be sent. International negotiations for such a force have been underway for months but remain complicated by mounting Sudanese opposition to a U.N. presence and the absence of a peace agreement among the warring groups in Darfur.

U.N.officials warn that the situation in Darfur is increasingly dangerous. “April seems set to be another month of spiraling violence,” Hedi Annabi, a senior U.N. peacekeeping official, told the Security Council in a closed-door briefing Tuesday.

U.N. Secretary-General Kofi Annan formally appealed to NATO in late March for help in fortifying the ability of the African Union force to restrain armed groups and ensure the safety of civilians. The alliance’s Military Committee is drafting a plan that administration officials expect will be presented to NATO’s political authorities later this month.

Nearly two months ago,President Bush signaled a new American commitment to the Darfur crisis, calling for a sizable U.N. force and a bigger role for NATO in the peacekeeping effort. His remarks February 17 were said by aides at the time to have grown out of the president’s frustration at the failure of the peace talks between Sudan’s government and Darfur rebels to stop the violence.

“When he made his public remarks, that put everything on a much faster pace,” the administration official said.

Still, the absence of major, visible gains in the weeks since Mr. Bush’s statement has fed skepticism about the ability of the administration and the rest of the international community to mount an effective response.

“My hunch is, we’re watching a bureaucratic slow-roll take place, but the danger is it’s happening as the situation on the ground is getting worse,” said Susan Rice, who served as an assistant secretary of state for Africa during the Clinton administration and now is a senior fellow at the Brookings Institution in Washington. “The administration has been in this knot of having called the situation genocide but then failing to do anything.”

The latest conflict dates from early 2003, when Darfur rebel groups took up arms against the Arab-led Islamic government in Khartoum, citing discrimination against the region’s black tribes. The Sudanese government bombed villages to force the rebels out and unleashed Arab militias that mounted a campaign of burning and pillaging.