ANKARA

The death of Chad's President Idriss Deby will create a "big vacuum" in the efforts to jointly confront the Boko Haram terrorists and the Islamic State West Africa Province, Nigerian President Muhammadu Buhari said late Tuesday.

"We must now strive to mobilize even greater collaboration to defeat the terrorists," Buhari said.

Faced with a growing threat from Boko Haram, Deby had increased Chad's participation in the Multinational Joint Task Force (MNJTF), a combined multinational formation comprising units from Niger, Nigeria, Benin and Cameroon.

Headquartered in Chad's capital N'Djamena, the MNJTF is mandated to bring an end to the Boko Haram insurgency that has killed more than 30,000 and nearly 3 million displaced.

Buhari said Deby played "a very active role in our regional joint collaboration in the military campaign against Boko Haram terrorists."

"He was a friend of Nigeria who enthusiastically lent his hand to our efforts to defeat the murderous Boko Haram terrorists that have posed grave security challenges not only for Nigeria but also our African neighbors, particularly Chad, Cameroon and the Niger Republic," he added.

The Chadian president died during military operations that pitted the Chadian armed forces against rebels in the north over the weekend, the army said on Tuesday.

On the frontlines of Chad's battle against rebels, Deby, 68, died just a day after his re-election for a sixth term.

The Chadian army announced late on Sunday that it had killed more than 300 rebels in the northern part of the Central African country.

The rebels were from the Front for Change and Concord in Chad (FACT), the army said in a press release. The fighting started a day after the April 11 presidential elections.