Mauritania's army says al-Qaida militants have attacked a military base in the West African nation.
A statement says Mauritanian forces pursued the militants as they fled toward neighboring Mali after Tuesday's attack in the town of Bassiknou.
There were no immediate casualty figures available.
Al-Qaida's North African affiliate has claimed responsibility for a series of attacks on Mauritanian military installations and government buildings.
They also have kidnapped dozens of foreigners across the Sahel region.
The militants said late Tuesday that they had killed 20 soldiers in an ambush late last month in the Wagadou region of Mali. Mauritanian officials said 15 militants and two soldiers were killed.