Three people were killed on Monday in a helicopter crash at an army base near Niger's capital Niamey.
"A Niger Armed Forces MI-17 helicopter, returning from a routine training flight, crashed while landing on the military airstrip from Niamey airport," the Nigerien Ministry of Defence said in a statement sent to AFP.
"Unfortunately the three crew members - an officer and a non-commissioned officer from Niger and an expatriate instructor - died on the spot despite the efforts of the emergency services to contain the fire," it added.
A commission of inquiry "was immediately set up to determine the causes of this tragic accident", continues the text.
Niger, a very poor Sahelian country, is trying to beef up its army, which has been fighting jihadist violence since 2015 on its immense territory, much of it desert.
Several parts are affected: the west, close to Mali and Burkina Faso where Al-Qaeda and the Islamic State group are present, and the south-east bordering Lake Chad and Nigeria, which has become a hideout for jihadists.
The border area between northern Benin and southern Niger, so far spared, has in turn been confronted for several months with the jihadist threat, according to the authorities.
Also on Monday, the Minister of Defence announced that "25 terrorists" were killed last week "after an air strike" in the region of Tillabéri in western Niger.
In its fight against armed Islamists, Niger benefits from logistical and training support from France, the United States, Italy, Germany and Belgium.
France and the United States both have military bases in Niger and Germany has a logistics base.