The youngster was followed by three of his siblings, who are all around half the size of a fully grown adult.

Father, Ato also managed to fit under the fence to join the others in their bid for freedom, while the mother lion Maya remained in the enclosure with another cub, Ayanna.

CCTV footage released by the zoo on Thursday shows the escape and resulting chaos as keepers arrived on the morning of November 2 to discover the lions outside their enclosure.

The lions can be seen prowling along the exterior fence line before keepers arrive with what appear to be rifles.

The zoo reported Maya called out to her missing cubs to return, which they eventually did after venturing several metres from the main enclosure.

"The cubs and father Ato made several attempts to re-enter the exhibit, and male cub Luzuko was the first to successfully do so," the zoo said in a statement.

"He was followed shortly after by female cub Zuri and male cub Khari."

While most of the lions were able to find their own way back under the fence, female cub Malika was tranquilised by the zoo's emergency response team and transported back to the dens.

Zoo officials said the lions would not be returned to the enclosure before Christmas as investigations continue into how the escape occurred, including an independent review by specialist engineers to advise on necessary repairs.

"The lions will continue to remain in an outdoor, back-of-house habitat pending findings of the specialist engineering review," the statement said.

Australian Associated Press