NAIROBI, Kenya — As rebels in Chad fought for a second day to take control of the nation’s capital, analysts said yesterday that the outcome of the attempted coup could have far-reaching implications for the Darfur conflict in neighboring Sudan.

Foreign observers said the military standoff remained unresolved. President Idriss Deby appeared to be holed up with a large force of loyal troops in his presidential palace.

The aid group Doctors Without Borders reported that scores of civilians had been wounded, mostly from errant gunfire. Looting has been reported in N’Djamena, the capital, and the French government evacuated at least 500 foreigners.

Rebels claimed to have seized control of the town of Adre, along the eastern border with Sudan, while Chadian authorities told reporters that the attackers had included Sudanese troops and had been repelled. Neither report could not be verified.

A collapse of Mr. Deby’s regime likely would be felt beyond Chad’s borders. Mr. Deby has been a big supporter of Darfur rebels in western Sudan, and his fall would threaten to tilt the balance of power in Darfur toward the Sudanese government, which is backing the rebel assault under way in Chad.

“This could be a big win for Sudan,” the special counsel for Human Rights Watch, the international advocacy group, Reed Brody, said. “The rebel alliance will be beholden to Khartoum. They will control one of the main access points and windows into Darfur.”

Chad is currently host to about 250,000 Darfur refugees who fled violence in western Sudan over the past four years. Chad also serves as an important gateway for humanitarian groups, journalists, human-rights activists, and peacekeepers, many of whom are unable to access Darfur through other areas of Sudan. Experts said that access could be at risk if a Sudan-friendly regime suddenly took control of Chad.

In addition, Darfur rebel groups use Chad as a safe haven and launching point for attacks against Sudanese government troops. Mr. Deby, who seized control of Chad through a coup in 1990, is from the same Zaghawa tribe as one of the main Darfur rebel movements. His government has supplied Darfur rebels with guns and allowed them to set up training camps along his border.

“If Deby goes, that could be a decisive blow for the Darfurian rebel operations in Chad,” a co-founder of ENOUGH, a grass-roots anti-genocide group, John Prendergast, said.

A weakened Darfur rebel movement would complicate mediation talks between the Sudanese government and guerrillas to end a conflict that has killed an estimated 200,000 people and displaced more than 2 million.

“It would shift the strategic balance in Khartoum’s favor and make it that much harder to get a [peace] deal,” Mr. Prendergast said.