Niger has confirmed that French special forces are protecting one of the country's biggest uranium mines.
President Mahamadou Issoufou told French media that security was being tightened at the Arlit mine after the recent hostage crisis in Algeria.
French company Areva plays a major part in mining in Niger - the world's fifth-largest producer of uranium.
Islamist militants kidnapped five French workers from the mine in Arlit three years ago.
Four of them are still being held - along with three other French hostages - and it is believed they could be in the north of Mali close to where French troops are battling al-Qaeda-linked militants.
Asked if he could confirm that French special forces were guarding the uranium mine, President Issoufou told channel TV5: "Absolutely I can confirm.
"We decided, especially in light of what happened in Algeria... not to take risks and strengthen the protection of mining sites," he added.
France's Agence France-Presse news agency said a dozen French special forces reservists were strengthening security at the site.
Areva gets much of its uranium from the two mines it operates in the country, at Arlit and Imouraren.
Last month, at least 37 foreign workers were killed when Islamist militants seized a gas plant at In Amenas, eastern Algeria.