An Algerian driver kidnapped last week in northern Niger has been released in neighbouring Mali, sources said.
The man had been abducted with a French tourist in a remote desert region close to the border with Mali and Algeria.
"Some people riding camels found him wandering. After some explanations, they took him to Algeria," a military source in Niger told Reuters.
Gunmen linked to al-Qaeda - which has seized several Westerners - were still holding the tourist, the sources said.
Some sources suggest he is being held in Mali.
The pair were taken near the town of Tiguidan Tessoun just days after four Saharan countries opened a military base to counter al-Qaeda in the Islamic Maghreb (AQIM).
The group is believed to earn money from ransom payments for hostages, although this is never officially confirmed.
It has also demanded the release of some of its captured militants in exchange for hostages.
In February, Mali freed four militants, sparking a row with Mauritania.
Mali's government denied accusations it was giving in to the militants' demands and said the men had served their time.
Two Italians were freed in Mali earlier this month after spending four months in captivity, but two Spaniards are still being held hostage.
Last year, AQIM killed a British hostage, Edwin Dyer.
The group emerged in early 2007, after a feared militant group, the Salafist Group for Preaching and Combat (GSPC), aligned itself with Osama Bin Laden's international network.
It has waged a campaign of suicide bomb attacks and ambushes in Algeria, and in recent years has become more active in the Sahara Desert, where governments struggle to impose their authority and gangs of smugglers, bandits and rebels operate alongside the militants.