Relations with Niger are of extreme importance for France, as the western African country is the last stronghold of the French armed forces in the Sahel region, the politician noted.
"So, if the new government in Niger, resulting from the present crisis, adopts the same attitude as Burkina Faso and Mali, which is very possible, it will be another very bad blow to the French influence in the region. Wait and see," Mariani said.
The uranium ore supplies from Niger play an even more important role, as France, together with other European countries, need them for their nuclear energy facilities and military projects, the politician added.
France and the United States have still not slapped any sanctions on Russian enriched uranium and continue to buy it, he said. Canada, Uzbekistan and Tajikistan could become alternative sources of uranium for the Western market, but the latter two are "friends of Russia," Mariani noted.
On Wednesday, members of the Nigerien presidential guard said in a statement broadcast on national television that they had overthrown the president, Mohamed Bazoum, closed borders and imposed a curfew in the country "until further notice." It came hours after the presidential guard detained the president at his residence and sealed off access to public offices in Niamey.
France withdrew troops from Mali last year and from Burkina Faso earlier this year, following coups in both countries, where the French military was deployed to help combat Islamist militant groups.