FILE - Mahamat Idriss Deby Itno, 37, the son of Chadian President Idriss Deby Itno, is seen during a military broadcast announcing the death of his father on state television Tuesday, April 20, 2021. AP
The mountainous Tibesti region is a traditional battleground between the army and rebel groups that have sought for years to oust the government in distant N'Djamena.
Army spokesman General Azem Bermandoa Agouna told AFP on Wednesday that 23 rebels had been killed and eight soldiers wounded since May 31, when the army attacked an insurgent column in the Kouri Bougoudi area.
The rebels belong to the National Front for Democracy and Justice in Chad (FNDJT) and the Military Command Council for the Salvation of the Republic (CCMSR), he said, giving what he described as the "final toll" from the fighting.
In contrast, the FNDJT said in a statement on Tuesday that it had "forced (the army) to retreat" and killed 15 soldiers, including two senior officers.
The conflicting figures could not be verified independently.
The Tibesti region abuts the border with Libya, which the rebels use as a rear base for attacks.
Lying in hostile terrain more than 600 kilometres (375 miles) from the capital, the region is notorious for illegal gold digging, armed groups and bandits.
The FNDJT and the CCMSR rank among the most powerful and active groups in the constellation of rebel forces in Chad.
The biggest, the Front for Change and Concord in Chad (FACT), launched a spring offensive in 2021 that was stopped by the army around 200 km north of N'Djamena, but the country's veteran ruler, Idriss Deby Itno, was killed during the fighting.
His son, General Mahamat Idriss Deby, took the helm immediately afterwards, heading a 15-member military junta that says it will hold elections by October 2024.