Niamey, Niger (CNN) -- An Islamist militant group has claimed responsibility for Thursday's deadly attacks on an army barracks and a uranium mine in Niger, saying they were responses to Niger's cooperation with France in a "war against Sharia," CNN affiliate BFMTV reported.
Twenty soldiers and five assailants were killed, and at least 30 other people -- including civilians -- were injured in attacks about 200 kilometers (124 miles) apart in Niger early Thursday, the African nation's defense minister said.
Karidjo Mahamadou said later security forces were in charge of the two sites, including one where an attacker had taken hostages.
"I ensure that the situation is under control and that the Niger security forces have renewed the vow to secure the country and the people," he said.
A spokesman for the Movement for Unity and Jihad in West Africa, or MUJAO, said that "thanks to Allah, we have carried two operations against the enemies of Islam in Niger," BFMTV reported.
MUJAO is among the radical Islamist groups that have been fighting Malian and French forces in Mali, which borders Niger.
Both attacks -- at the army barracks in Agadez in central Niger and a Somair uranium mine in Arlit in northern Niger -- happened about 5 a.m., Niger Domestic Affairs Minister Abdou Labo said.
In Agadez, a regional capital to the southeast of Arlit, a truck carrying armed assailants and explosives detonated in front of the army barracks, Labo said.
A battle ensued in which the 20 soldiers were killed, Labo said. A breakdown of how many deaths were attributable to the bombing and how many happened in the battle wasn't available.
The surviving assailant closed himself in a building with cadets and threatened to detonate explosives, Labo said.
Mahamadou didn't say whether the suspect had been captured when he said everything was under control.
At the Somair mine, operated by French nuclear power group Areva, a truck with explosives blew up at the gates, killing two assailants, Labo said. At least 14 civilians were wounded, Mahamadou said.
Areva said the injured included at least 13 workers.
MUJAO spokesman Abu Walid Sahraoui said the group "attacked France and Niger for its cooperation with France in the war against Sharia," BFMTV reported Thursday.
France deployed about 4,000 troops to Mali, the country directly to Niger's west, in January to drive out Islamist militants -- including MUJAO members -- who had attempted to take control of the country.
Islamic extremists with links to al Qaeda carved out a large portion of northern Mali last year, taking advantage of a chaotic situation after a military coup in March 2012. France took military action this year after the militants began to push into the southern portion of the country.
MUJAO is a splinter group of Al Qaeda in the Islamic Maghreb, according to the United Nations.
France strongly condemned Thursday's attacks, the French foreign ministry said. French Foreign Minister Laurent Fabius spoke with his Nigerien counterpart and expressed France's solidarity with Nigerien authorities in the fight against terrorist groups, the ministry said.
Niger, a former colony of France, gained independence in 1960.
Journalist Ibbo Daddy Abdoulaye reported from Niamey, Niger. CNN's Jason Hanna and Pierre Meilhan reported and wrote from Atlanta. CNN's Amir Ahmed also contributed to this report.