The U.N. Security Council and Secretary-General Kofi Annan have condemned the rebel offensive in Chad. Diplomats expressed concern about the rebels' links to the neighboring Darfur region of Sudan.

Hours after Chadian forces fought off a rebel assault on the capital, N'Djamena, the U.N. Security Council called on the attackers to end the violence. The Council president, Chinese Ambassador Wang Guangya, read a statement linking the attack to worsening conditions along the border between Chad and Sudan.

"The members of the Council express their deep concern regarding the deteriorating situation in Darfur and the recent attacks by armed groups in Chad," said Wang Guangya. "The members of the Council condemn any attempt to seize power by force, and call on the rebels to put an end to violence and to participate in the democratic process."

The statement made clear that it also referred to recent armed attacks on camps housing many of the 200,000 Sudanese who have fled vicious fighting in Darfur over the past three years.

France, the former colonial power in Chad, says the rebels who attacked Ndjamena Thursday appeared to be isolated units, and that the main rebel force had been halted outside the capital.

France's U.N. ambassador, Jean-Marc de La Sabliere, said he had been told that the attacking force consisted of about 800 well-equipped fighters. But he noted that the Security Council is gravely concerned by reports that the attackers were operating from bases in Darfur.

"Darfur is today on top of the agenda of the Security Council," said Jean-Marc de La Sabliere. "It's a very complex issue, and what is happening now in Chad is complicating more and more this issue. The links between Darfur and Chad are really worrisome, so we want the African Union totally engaged to try to settle the issue."

De La Sabliere linked the Chadian rebel force to Arab militias in Darfur known as janjaweed. The pro-Sudanese government militias are accused of carrying out a campaign of ethnic cleansing against black African villagers in Darfur.

The Khartoum government, however, has denied backing the Chadian rebels.

The United Nations is making preparations to take over a beleaguered African Union peacekeeping force in Darfur in the coming months. U.N. officials say the 7,000 strong force has been largely ineffective in efforts to stop what many are calling an ongoing genocide in an area the size of France.

But Sudan's government has expressed strong opposition to the U.N. takeover, and Secretary-General Kofi Annan's envoy to the region recently told the Security Council that the takeover plan appears to be unraveling in the face of fierce Sudanese pressure.

In a statement Thursday, Secretary-General Annan said he was greatly troubled by the worsening security situation in Chad. In a separate statement, U.N. High Commissioner for Refugees Antonio Guterres appealed to all sides in Chad to respect the civilian character of camps for Darfur refugees along the border with Sudan.

The agency operates 12 facilities in eastern Chad housing as many as 200,000 people, and officials this week reported armed men had entered one camp during a food distribution to 17,000 refugees.