A video released by the North African branch of Sunni militant group Al Qaeda apparently shows seven Western hostages are still alive .
Mauritanian news agency ANI, which received the footage from the group, says it shows four Frenchmen who were kidnapped from a uranium compound in Niger three years ago.
The captives, which include a Dutchman, a Swede and South African, were kidnapped in the north of Mali in November 2011 and seemed in good health, ANI reported.
The French foreign ministry said it believed the video was credible, BBC reported.
The video was apparently sent to ANI by the Al Qaeda in the Islamic Maghreb (AQIM).
"Based on an initial analysis, the video seems credible to us and provides new proof of life of the four French hostages kidnapped in Arlit (northern Niger) on 16 September 2010 ," French foreign ministry spokesman Philippe Lalliot said, according to BBC.
Although it is unclear when the video was made, ANI reported that the videos made by the hostages was recorded in June.
In the video, French national Daniel Larribe, 61, said: "I am in good health but threatened with death,'' according to BBC.
He said that he held French authorities responsible for his fate, ANI said. He gave no further details.
The three other French hostages were named as Pierre Legrand, Thierry Dol and Marc Feret, according to the ANI report.
Dutch hostage Sjaak Rijke, Swedish hostage Johan Gustafsson, and South African hostage Stephen Malcolm were kidnapped nearly two years ago from a hostel in Timbuktu in an attack that left a German man dead.
This is the first video that shows the men since France sent troops to Mali in January, after Al Qaeda-affiliated militants threatened to overrun the capital Bamako, BBC reported.
French President Francois Hollande said in July that France was "doing everything" to secure the hostages' release but would not comment further for fear of complicating "a situation which is bad enough", BBC said.