Chad officials initially said as many as 30 people may have died when the mine caved in on Tuesday in Kouri Bougoudi, in Tibesti province, near the Libyan border, an area rife with illicit mining and smugglers.
Another source who was part of a mission to visit the area also confirmed the new death toll.
"There are 37 injured, including 21 seriously," the second source said.
Tibesti is largely lawless and home to numerous gangs and traffickers seeking to profit from a gold rush in the area.
Clashes in January between Arab miners from Libya and miners from Chad's Ouaddai community left "dozens" dead, according to security and mining sources.
Kouri Bougoudi has been the centre of clashes among ethnic, local and foreign groups since 2012 and 2013 after the discovery of gold deposits there.