The Cross River gorillas are said to be the most endangered gorilla subspecies, numbering only around 300 in the wild.
They were known to live in some mountainous areas in Nigeria and neighbouring Cameroon but are rarely seen.
The recent images of the animals with a number of infants were captured in Mbe mountains in southern Nigeria, according to conservationists.
The Cross River gorillas are naturally wary of humans and have subtle distinctions from other species - such as smaller heads, longer arms and lighter-coloured hair.
The Wild Conservation Society says it is working closely with local communities and the authorities in Nigeria’s Cross River state to protect the gorillas.