Rebels threaten to march on capital as Chad reels from president's battlefield death

Rebel forces set their sights on Chad's capital N'Djamena on Wednesday following the battlefield death of President Idriss Deby, threatening to bring more disruption to a country vital to international efforts to combat Islamist militants in Africa.

Schools and some businesses were open in N'Djamena on Wednesday but many people had opted to stay home and the streets were quiet, a Reuters witness said.

Authorities imposed a nightly curfew and closed land and air borders after Deby's death was announced. A 14-day period of national mourning is being observed.

Deby, 68, died on Monday on the frontline in a battle against Libya-based fighters, shocking the nation and raising concerns among Western allies who had long seen him as an ally in their fight against Islamist groups.

He had been in power since 1990 and had just been announced winner of a presidential election that would have given him a sixth term in office. His son, Mahamat Idriss Deby, has been named interim president by a transitional council of military officers.

Deby, who often joined soldiers on the battlefront in his military fatigues, was visiting troops after rebel group Front for Change and Concord in Chad (FACT) invaded from Libya and advanced hundreds of miles towards the capital.

FACT rejected the military's transition plan and said they would press on with their offensive on the capital.

"Chad is not a monarchy. There can be no dynastic devolution of power in our country," FACT said in a statement.

Opposition politicians also called for a move back to civilian rule.

Deby had won friends abroad by sending his well-trained army to fight jihadists including Boko Haram in the Lake Chad Basin and groups linked to al Qaeda and Islamic State in the Sahel.

His main ally, France, has about 5,100 troops based across the region as part of international efforts to fight the militants, including its main base in N'Djamena.

His death, which Paris described as the loss of a courageous friend, poses questions about stability in the region and inside Chad itself. As well as the rebel threat, the military is divided and the opposition to Deby's authoritarian rule had been growing.

"The potentially explosive consequences of President Déby's death cannot be underestimated – both for the future of Chad and across the region," Human Rights Watch said in a statement.

The New York-based organisation said the military council must respect human rights and ensure that civilians were protected. It also called for a swift transition to democratic civilian rule, and free and fair elections.

"For years, international players have propped up Déby's government for its support for counterterrorism operations... while largely turning a blind eye to his legacy of repression and violations of social and economic rights at home," HRW said in a statement.