Mauritania's authorities say they have arrested nine people in connection with the shooting of four French tourists last month.
The nine appeared at a district court in Aleg, the town near where the tourists were killed.
Prosecutors in Mauritania alleged the suspects are linked to a group allied to al-Qaeda.
The tourists - apparently members of the same family - were shot by gunmen as they stopped for a roadside picnic.
A fifth person, said to be the father of the family, survived and has been transferred to Senegal for treatment.
Such an attack is rare in the south of Mauritania, a former French colony which enjoys relative stability. The north of the country is generally regarded as less safe for travellers.
The gunmen opened fire with automatic weapons, before speeding off in a car that was later recovered in Aleg, about 250km (160 miles) east of the capital Nouakchott.
The victims were initially reported to have been robbed, though the interior ministry now says they were not, the Associated Press news agency reports.
In their statement, prosecutors in Nouakchott said murder suspects were thought to belong to al-Qaeda in the Islamic Maghreb - a group formerly known as the Salafist Group for Preaching and Combat.