Paris, Nov 28 (AP) An Islamic State group affiliate claimed responsibility Thursday for a helicopter collision that killed 13 French soldiers earlier this week in Mali, while France said it will reassess its military operation in West and Central Africa after its deadliest toll in nearly four decades.

The Islamic State in the Greater Sahara statement, with no evidence, came almost three days after the low-flying helicopters collided on a moonless night while pursuing extremists near the border with Niger.

An investigation has begun into the cause of the crash and the flight data recorders have been found.

French military spokesman Col. Frederic Barbry said the military would not comment on the claim. Shortly after the crash, Army Chief of Staff Gen. Francois Lecointre said the helicopters had been supporting French forces on the ground pursuing fighters with the IS affiliate.

A national memorial ceremony will take place Monday in Paris.

French President Emmanuel Macron told reporters that “our mission there is important, yet what we are now living in the Sahel leads us to look into all strategic options.” He said the government and military will work on the issue in the coming weeks.

Macron this week defended France's largest overseas military mission, which involves 4,500 troops, saying it is aimed at enhancing France's own security and providing support to African countries.

The helicopter collision drew global attention to an emerging front for IS-linked groups as IS loses strength in its core area in Syria and Iraq.

Counterterror officials have worried about the risk of fighters fleeing that region for Africa's sprawling Sahel, the arid strip south of the Sahara Desert.

Before his death this year, IS leader Abu Bakr al-Baghdadi congratulated "brothers" in Mali and neighboring Burkina Faso for pledging allegiance.

Extremist groups have been using forested areas along the poorly defended border areas of Mali, Niger and Burkina Faso to find refuge while spreading south into more populated areas. Nearly half a million people have fled their homes this year alone in once-peaceful Burkina Faso.

France has been outspoken on the need for more global support for counterterror operations in the Sahel, especially funding for the five-nation G5 Sahel counterterror force that was created two years ago.

France intervened in Mali in 2013 after extremists seized control of major towns in the north and implemented a harsh version of Islamic law. They were forced back into the desert, where they have regrouped.

A new surge in extremist attacks in Mali has killed well over 100 local troops in the past two months, with IS often claiming responsibility. The extremists loot military posts and profit from mining operations.

Public frustration in Mali over the insecurity has been directed at the French military presence as well.

The crash was France's highest military toll since 1983, when 58 paratroopers were killed in a truck bombing in Lebanon. (AP)

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