Dublin Zoo is investigating after a child gained access to a rhino enclosure over the weekend.

Images posted to social media on Saturday show the young boy standing inside the African Savanna enclosure, close to an adult on the other side of the fence. 

The child can be seen looking out from rocks along the plain's perimeter as a middle-aged man holds his hand.

One onlooker said the boy remained on the wrong side of the fence for several minutes. 

@ccferrie @DublinZoo this man had the child in behind the fence for good 20 minutes ! pic.twitter.com/BzhhUW5Obr

— Adrianna Straszewska (@Adriannasss) July 31, 2016

A spokesperson for the zoo told Newstalk.com that the incident is being “reviewed” but that they were satisfied correct safety standards were in place.