Earlier reports said 87 bodies were found, but security forces later confirmed that 92 bodies were found, CNN reported.
The migrants were making their way to Algeria from Niger when their convoy broke down, Azaoua Mahaman, of the Synergie nongovernmental organization, said Thursday. They died of dehydration.
Rescue worker Almoustapha Alhacen said the corpses were severely decomposed and partly eaten, probably by jackals, the BBC said.
Niger is along a major migrant route between sub-Saharan Africa and Europe.
Alhacen said one of the vehicles the migrants were using became inoperable after they left Arlit in late September or early October.
Security officials have said the second vehicle broke down as it was returning to Arlit for parts. Some of the group began walking, including at least 10 people who made it back to Arlit and alerted others, the rescue worker said.
Five bodies were found Monday and on Wednesday volunteers and soldiers found other corpses about 6 miles from the Algerian border, the BBC said.