Niamey, Niger — Hundreds of jihadists attacked a Niger military camp near the border with Mali, killing 71 soldiers, the defense ministry said Wednesday. Tuesday's attack in Inates in the western Tillaberi region was the deadliest on Niger's military since the country's Islamist militant violence began in 2015.

"Sadly, we regret to announce the following toll: 71 military personnel killed, 12 injured. Others missing," the defense ministry said in a statement aired on national television.

The attack was carried out by "heavily armed terrorists estimated to number many hundreds," the statement said, adding that "a substantial number of terrorists were neutralized." The SITE intelligence group, which monitors jihadist media, said fighters who have sworn allegiance to ISIS claimed responsibility for the attack.

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The group, known as ISIS in West Africa or ISWAP, is a Boko Haram splinter faction. It has about 3,000 men grouped in the Lake Chad region where northern Cameroon converges with Nigeria, Niger and Chad.

CBS News correspondent Debora Patta said it was the deadliest attack on Niger's defense forces in memory. The fighting lasted three hours, during which time the militants hit the base with shelling, mortars and suicide vehicle bombs.

Patta noted that the attack occurred just 30 miles from the scene of an ambush by jihadists in neighboring Mali that left four U.S. soldiers dead, along with five Nigerien forces, five years ago.

Caught between jihadist groups

Niger forces have been fighting Boko Haram militants on the southeast border with Nigeria and jihadists allied with ISIS in the west near Mali and in the northeast near Libya.

Niger President Issoufou Mahamadou cut short a visit to a peace and security conference in Egypt to return to Niamey, the presidency said on Twitter.

Army reinforcements were rushed to the scene and the situation on Wednesday was "under control," the defense ministry said, stressing that a search for the assailants was underway, though they had "fled beyond our borders."

Tuesday's attack prompted French President Emmanuel Macron to postpone a meeting scheduled for next week in the southwestern French town of Pau, where he and five presidents from north and west Africa were due to discuss security in the region.

The meeting will now take place early next year.

Niger is part of a five-nation anti-jihadist task force known as the G5, set up in 2014 with Burkina Faso, Mali, Mauritania and Chad.

Nigerien commandos simulate a raid on a militant camp during the U.S. sponsored Flintlock exercises in Ouallam, Niger, in this April 18, 2018 file photo. Aaron Ross/REUTERS

Niger's council of ministers has extended for another three months a state of emergency in place since 2017 in several departments to fight against jihadist attacks, handing additional powers to security forces.

Thousands of civilians and soldiers have died in violence across the vast Sahel region, which began when armed Islamists revolted in northern Mali in 2012.

The conflict has since spread to the center of Mali and to neighboring Burkina Faso and Niger. Attacks continue, despite the 4,500 French troops deployed in the region as part of Operation Barkhane to help local forces.

Thirteen French soldiers were killed in Mali last month when two helicopters collided during an operation against jihadists in the country's restive north, in the heaviest single loss for the French military in nearly four decades.