Idriss Déby, the veteran president of Chad, is dead, national radio in the central African state has said.
A statement from the military said the 68-year-old ruler, in power for 30 years, had been killed “on the battlefield” after being injured fighting rebels but gave no further details.
Déby last week won a sixth term in presidential elections. The poll prompted an invasion of Chad by rebels based in Libya, which military officials had said was repulsed at the weekend.
Officials had said the veteran politician would not give a victory speech after the polls because he had travelled to the frontlines to take charge of military operations.
Déby took control of the strategically located country in an armed rebellion in 1990. He was one of Africa’s longest-serving leaders and a close ally of western powers battling Islamist militants in west and central Africa.
But he has faced repeated insurgencies in the desert north and was also dealing with mounting public discontent over his management of oil wealth and crackdowns on opponents.
The unrest has raised alarm bells among western countries, which have seen Déby as an important ally in the fight against Islamist extremist groups, including Boko Haram in the Lake Chad Basin and groups linked to al-Qaida and Islamic State in the Sahel.
The death of Déby will underline the growing instability of the Sahel region, where a complex combination of economic, social, political and environmental factors is fuelling a series of crises.