Authorities in Guinea-Bissau have arrested two people over the shooting of four French tourists in Mauritania.
The men, both from Mauritania, were arrested in a hotel in the capital, Bissau, police said.
The tourists - apparently members of the same family - were shot by gunmen as they stopped for a roadside picnic near the town of Aleg last month.
At least nine people have been arrested in Mauritania. Prosecutors say they are linked to a group allied to al-Qaeda.
A fifth person, said to be the father of the family, survived the attack - 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.
A Guinea-Bissau police official told Reuters news agency the authorities had arrested the Mauritanians at the request of France.
She gave no further details.
The French tourists were killed on 24 December.
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.
Prosecutors in Nouakchott say the suspects are thought to belong to al-Qaeda in the Islamic Maghreb - a group formerly known as the Salafist Group for Preaching and Combat.