The leader of the Green Party in NI has said questions must be asked about safety at Belfast Zoo after a chimpanzee escaped from its enclosure.
Clare Bailey said that in light of this and an incident last month in which a red panda escaped she had concerns for "animals and humans".
Videos taken by visitors show a chimpanzee on a path, while other chimps remained on the enclosure wall.
Belfast Zoo said Saturday's incident was a "highly unusual event".
A spokeswoman said additional checks were being carried out after the chimpanzees made an improvised ladder from a large tree branch propped up against a wall.
"We would like to reassure the public that Belfast Zoo is fully committed to providing a safe and enjoyable experience for all our visitors," she said.
It is believed that the trees in the chimpanzees' enclosure had been weakened by recent storms making them easier to break up.
"Zookeepers carry out a range of checks as part of their daily duties, including ensuring enclosures are free from objects which could pose a security risk to animals or visitors," the spokeswoman added.
"Zoo management is assessing whether the tree branch used in the escape fell after morning checks had been completed."
Families described their shock at coming across a chimpanzee on one of the zoo's paths.
Chantal Baxter, from Larne, said "one of the big chimpanzees just appeared from behind a bush".
Danielle Monaghan, from Holywood, was "petrified" the chimp might "attack or take the kids".
But the mother of two said the animal was "not aggressive" and "just watched" and therefore the experience had been "amazing".
Ms Bailey said it was "lucky" no-one came to any harm.
"I've seen videos of the escape and it shows it was cool, calm and well executed," she said.
"We need to really start looking at what's going on at Belfast Zoo.
"I would be keen to meet up with the zoo (managers) and have these conversations."
In January, a ared panda called Amber went missing from the zoo overnight before being discovered in a nearby garden.
Alliance North Belfast Councillor Nuala McAllister said she had contacted Belfast City Council, which runs the zoo, about a review into the containment of animals, with a particular focus on safety measures.
"While Belfast Zoo carries out good work in terms of conservation and breeding programmes, that is simply not good enough and we need to ensure it doesn't happen again," she added.
Belfast City Council said one chimpanzee "briefly" left its enclosure on Saturday afternoon.
"Zookeepers were present as the chimpanzee quickly returned from an adjacent wall to the rest of the group inside the enclosure," a spokeswoman said.
The zoo's Alyn Cairns said the zoo's chimps were "quite cowardly" so went back into their enclosure themselves during the incident, which happened as the zoo was closing up for the day.
"We like things to be natural in their enclosure, to have trees in it, but we will review it," he added.
"We may have to remove the trees or make them a smaller level, although we don't want to do that."
The chimpanzees were locked in their inner enclosure after the great escape.