The blast destroyed the home of Mahamat Saleh Arim, deputy commander of the presidential guard and a close ally of President Idriss Deby Itno, an AFP journalist at the scene near the Adji Kossei airbase said.

The warhead struck just metres from the Chad headquarters of anti-jihadist Operation Barkhane, the French-led military campaign fighting militants in the region.

"An investigation is underway to determine the circumstances of this incident," said Youssouf Tom, public prosecutor at the N'Djamena High Court, who visited the scene.

Two women and two children were killed, an air force official said.

"The plane was taking off when the bomb broke loose, and hit a private residence in the city that houses soldiers' families next to the airbase," an air force officer added on condition of anonymity.

Russian-made Sukhoi jets used by the Chadian air force at the base were recently involved in strikes against Boko Haram militants in the Lake Chad region.

That massive operation followed a militant attack on a Chad army base in March that killed 98 troops. At least 150 Chadian soldiers have been killed in the area since mid-March.

Deby has said his country's troops, who have been fighting jihadists in the Lake Chad region and the Sahel, will no longer take part in military operations outside national borders.