UNITED NATIONS — Fearing that the deepening crisis in Chad will have regional implications, including in the neighboring Darfur region of Sudan, the Security Council yesterday gave France and other regional players the authority to secure the hold on power of Chad’s president, Idriss Deby, whose government is facing a stiff armed rebellion.

Among the countries that backed yesterday’s non-binding statement was one of the Security Council’s newest members, Chad’s northern neighbor, Libya. The Gadhafi regime has for decades meddled in its neighbors’ tribal and factional disputes, often supplying opposite factions with arms, only to emerge later as mediator. Yesterday’s council statement lent support for the African Union conferring such a meditation role in Chad on Colonel Gadhafi and on Congo’s President Nguesso.

For Washington — which yesterday announced the evacuation of most American officials from Chad, leaving only a skeleton staff in the Ndjamena embassy — the threat to General Deby’s government represents a warning that the dire situation in Darfur may soon destabilize the region further. The Bush administration has defined the atrocities in Darfur as genocide, and the plight of villagers at the Sudanese western province became a cornerstone of American campaigns led by human rights organizations, Hollywood stars, and top politicians of both parties.

Yesterday, America assumed a supporting diplomatic role, behind Chad’s former colonial power, France. “The French have the expertise and the lead on this issue,” America’s U.N. ambassador, Zalmay Khalilzad, said yesterday. “Should they decide to do more, they have the support of the Security Council,” he added. For now, France has only slightly beefed up its military force in Chad to 1800 troops, bringing existing French troops from neighboring Gabon to assure the safety of foreigners in Ndjamena.

“We are not involved in this war,” the French foreign minister, Bernard Kouchner, said yesterday after the council’s decision. If France is invited to do more by the African Union with the backing of the Security Council, “We will see,” Mr. Kouchner added. Diplomats here say the French public widely supports involvement, including by the military, in the former colony. Yesterday’s council’s statement gave the green light for such involvement if General Deby’s government is threatened further.

Over the weekend, hundreds of rebels — dissatisfied with General Deby’s perceived favoritism toward his own minority Zagawa clan, combined with his inability to improve the welfare of the citizens despite growing oil revenues — stormed Ndjamena.

Although Khartoum denies it, Western diplomats say Sudan is the real power behind the rebellion. An estimated 400,000 Darfur refugees have fled Sudan across the border into Chad, where they reside in makeshift camps, dependent on foreign aid for survival. Sudan has accused Chad of using the refugee camps as launching pads for Darfur’s anti-government rebel groups.

The weekend-launched rebellion is expected to complicate the deployment of a European Union humanitarian mission in Chad, as well as in the Central African Republic, which started only recently.

Western diplomats said yesterday they also fear that even the few non-African countries that have pledged troops and equipment for a 25,000-troop force in Darfur under the command of the United Nations and the African Union may now withdraw their support.