Mauritania has launched a military operation against militants linked to al-Qaeda along the border with Mali, officials in the two countries say.
Some unconfirmed reports say the fighting has moved across the border into Mali itself.
Al-Qaeda in the Islamic Maghreb (AQIM) has been behind numerous attacks in north-west Africa.
France believes the group is behind the kidnapping of seven people, including five French citizens, in Niger.
Initial reports quoted Mauritanian security sources saying the clashes were taking place near the border with Mali’s Timbuktu region.
A Malian security source was later quoted by AFP as saying fighting was taking place in Mali, at Hassissidi, about 100km (60 miles) north of Timbuktu, but this could not be confirmed.
AQIM emerged in 2007 after an Algerian militant group aligned itself with Osama Bin Laden’s international terror network.
It has carried out suicide attacks and ambushes in Algeria, and in recent years become more active in the Sahara, where governments struggle to impose their authority.
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