The barrier at the gorilla exhibit at Cincinnati Zoo in the US was not up to standard when a three-year-old boy fell inside the enclosure.

The incident on May 28th led to the shooting dead of a gorilla called Harambe, who had grabbed the child.

The child - who was visiting the zoo with his mother and relatives - was dragged around the enclosure for several minutes before zoo staff shot the gorilla.  

Federal inspectors have found the actions of the zoo team were justified as the child was in 'life-threatening danger'.

A spokesperson for the US Department of Agriculture told NBC: "[The barrier] was in compliance until May 28th and then it was found to be not in compliance as it did not restrict public access from the nonhuman primate."

The Cincinnati Enquirer suggests that that report's findings are a complicated way of saying "everything would have been fine at the zoo had a child not fallen into the gorilla exhibit, but because one did, the barrier failed".

In a statement responding to the report, the zoo said: "In its 38-year history, the barrier system at Gorilla World has always been found compliant during USDA inspections, including one conducted in April of 2016. Following the incident this May, we modified the barrier to reassure the public and our visitors."

Cincinnati Zoo Director Thane Maynard said: “We remain committed to visitor and animal safety and will continue to work with the USDA and the Association of Zoos and Aquariums (AZA) to ensure that our exhibits meet or exceed standards."

The killing of Harambe sparked international outrage and mourning, particularly on social media sites.