Niamey - Islamist militants staged brazen twin car bomb attacks on an army base and a French-run uranium mine in Niger on Thursday, killing at least 19 people and taking several trainee army officers hostage in the impoverished west African nation, the government said.
The unprecedented attacks were claimed by an Islamist group as revenge for Niger's involvement in a French-led military offensive in neighbouring Mali and come just four months after Al-Qaeda linked militants seized a desert gas plant in neighbouring Algeria in a siege that left 38 hostages dead.
The Movement for Oneness and Jihad in West Africa (MUJAO), one of the Islamist groups which seized control of northern Mali last year before being driven out by French-led troops, claimed the near simultaneous bombings at the Agadez army base and the French majority-owned uranium mine in Arlit.
"Thanks to Allah, we have carried out two operations against the enemies of Islam in Niger," MUJAO spokesman Abu Walid Sahraoui told AFP.
"We attacked France and Niger for its cooperation with France in the war against sharia (Islamic law)."
Eighteen soldiers and a civilian were killed along with four attackers at the army base in Agadez, the largest city in northern Niger, while around 50 people were wounded at the mine, Interior Minister Abdou Labo said.
"A fifth bomber has locked himself up in an office with several trainee officers as hostages (at Agadez)," Labo said. "We are taking action to arrest the bomber and free the hostages."
Defence Minister Mahamadou Karidjo described the attackers as "redskins", in a reference to members of the country's Tuareg and Arab groups.
Agadez resident Barka Sofa said he heard a strong explosion outside the base followed by heavy weapons fire, while a local journalist reported heavy damage inside the camp.
"All the streets of Agadez are blocked. The army is sweeping the city," Sofa added.
Some 30 minutes after the first blast at the base, a suicide bomber blew up an explosives-laden four-by-four at the Somair uranium mine and processing facility as employees reported for work at the site, which is majority-owned by France's Areva and is located some 250 kilometres (150 miles) north of Agadez.
"A man in military uniform driving a four-by-four packed with explosives mixed in with the Somair workers and blew up his vehicle in front of the power station at the uranium treatment facility," an employee told AFP.
"Company managers told us the suicide bomber was killed in the explosion," he added, saying the blast had caused damage but had not stopped work at the site.
Labo said almost all of the some 50 wounded there were security agents.
Somair is 63.6-percent-owned by Areva and 36.4-percent-owned by SOPAMIN, the agency that manages Niger's state mining interests.
The attacks come some four months after the seige in neighbouring Algeria that left 38 hostages dead, including 37 foreigners, in what the Islamists also described as a retaliatory attack for France's action in Mali.
France pledged its "full solidarity with the Nigerien authorities in the fight against terrorist groups," said foreign ministry spokesman Philippe Lalliot.
Areva condemned the blast as a "terrorist attack" on its website and said Nigerien authorities had stepped up security measures at its facilities.
Niger is part of the African-led Support Mission to Mali (AFISMA), a regional military mission launched to help reclaim northern Mali from Al-Qaeda in the Islamic Magreb (AQIM) and two allied Islamist groups that seized the vast desert territory in the chaotic aftermath of a March 2012 military coup.
French troops have so far led the operation against the Islamists, which was launched in January and has pushed the radicals from the territory they had brutally ruled.
Islamist groups have carried out several kidnappings in Niger in recent years, especially in the north.
Seven employees of Areva and one of its subcontractors were abducted in September 2010 by AQIM. Four Frenchmen are still being held by their kidnappers.