The scientific mission, conducted over five days in late July some 30 kilometres (nearly 19 miles) from Fada, the main town in Ennedi West, brought together Chadian archaeologists and geologists from universities in N'Djamena and Abeche.

The Natural and Cultural Reserve of Ennedi (RNCE) was created in 2018 in the Chadian province, which stands at the crossroads with Libya and Sudan and is home to a rich archaeological heritage.

Tens of thousands of engravings and paintings can be found on the rocky walls across the vast reserve's more than 50,000 square kilometres (19,305 square miles).

The head of the scientific mission funded by the group, Mahamat Ahmat Oumar, said 1,686 sites had been catalogued so far.