Twisted metal lies at the site of a morning car bomb attack inside a military camp in Agadez, in northern Niger, Thursday, May 23, 2013. (Stringer/AP)

Suicide bombers in Niger detonated two car bombs simultaneously Thursday, one in a military camp in the desert city of Agadez and another in the remote town of Arlit at a French-operated uranium mine, killing a total of 26 people and injuring 30, according to officials in Niger and France.

A surviving attacker took a group of soldiers hostage, and authorities were attempting late Thursday to negotiate their release.

The timing of the attacks, which occurred more than 100 miles apart, and the fact that the bombers penetrated a well-guarded military installation and a sensitive, ­foreign-operated uranium mine highlight the growing reach and sophistication of the Islamist extremists based in neighboring Mali. Both attacks were claimed by the Movement for Oneness and Jihad in West Africa, an al-Qaeda spinoff that had vowed to avenge the four-month-old French-led military intervention that ousted them from towns in Mali’s north.

Most of the deaths were in Agadez, 600 miles northeast of the capital, Niamey, where the attackers punched their explosives-laden car past the defenses at a military garrison and detonated it inside the base, killing 20 soldiers and injuring 16, said Nigerien Defense Minister Mahamadou Karidjo. Three suicide bombers died, but a fourth escaped and grabbed a group of military cadets, the interior minister said.

At the same time, a group slipped inside a uranium mine operated by the French nuclear giant Areva more than 150 miles northeast of Agadez. Their car exploded once it was inside the campus, injuring 14 Areva employees, one of whom died later, according to the French corporation and witnesses. Two suicide bombers also were killed, the Defense Ministry said.

In January, when France scrambled warplanes over Mali and sent in ground troops to try to take back the country’s militant-held north, the extremists vowed to hit back not just at French interests, but also at the African governments that helped them. The bombings Thursday were the most damaging attacks by the Mali-based jihadists to date and hit both an important French asset and the military of Niger, which sent 650 troops to Mali.

Striking Arlit was especially symbolic. Niger produces up to 40 percent of France’s uranium imports — a considerable amount, given that France derives 80 percent of its energy from nuclear power, according to an analysis released Thursday by the global intelligence firm Stratfor.

— Associated Press