GNN Ads
The suicide attacks on Thursday killed 24 soldiers and one civilian and damaged machinery at Areva's Somair mine in the town of Arlit, a supplier of uranium to France's nuclear power program.
Militants said the raids were in retaliation for Niger's role in the French-led war on Islamists in Mali.
French forces have killed hundreds of Islamist gunmen in Mali while those who escaped the raids have scattered across the desert in the north of the country and a vast region full of uncontrolled borders.
"According to the information we have, the attackers came from southern Libya," Issoufou said of the dawn attacks in Niger which raised fears that Mali's conflict could spread to neighboring West African states.
"I know the Libyan authorities are trying hard. But Libya continues to be a source of instability," the president said.
He did not give details on who the gunmen were, but Mokhtar Belmokhtar, a one-eyed veteran of al Qaeda's North African operations, said that his Mulathameen brigade organized the raids with the MUJWA militant group.
Thousands of gunmen and tons of weapons and ammunition flowed south, mainly to Mali, after the fall of Libya's former leader Muammar Gaddafi in 2011.
A mix of Islamist and separatist rebels then seized control of the north of Mali before the French operation launched in January dislodged them from the towns they controlled.
Niger has for weeks warned that Libya was the next potential safe haven for militants. (Reuters) (GNN)