The Islamic State's West Africa Province (ISWAP) claimed responsibility for Monday's accident, the heaviest single loss for the French army in nearly four decades.

"It's totally false," General Francois Lecointre told Radio France International.

"The truth is that there was a collision during a very complex combat operation," he said.

"The French army is telling the truth: we owe it to our soldiers and to the families of our dead colleagues."

ISWAP said its fighters ambushed a French convoy near Indelimane village, in the Menaka area, and opened fire on one of the helicopters that arrived in support.

"After staggering in flight, it then collided with another helicopter, killing 13 Crusaders," said an ISWAP statement carried on the SITE intelligence group website.

The general said there was no attack by the jihadists that the army was pursuing near the borders with Burkina Faso and Niger.

"There was no withdrawal of an aircraft in the face of fire from the jihadists," he added.

The general said the helicopter black boxes were being analysed for details of exactly what happened.

The accident brought to 41 the number of French troops killed in the Sahel region since Paris intervened against jihadists in northern Mali in 2013.

Since then, armed groups affiliated with IS, Al-Qaeda and others have advanced into southern Mali as well as neighbouring Burkina Faso and Niger.