Belfast Zoo could face closure if councillors pass a Sinn Fein motion declaring the caging of animals is "unethical and wrong".
A spokesperson for the zoo said the attraction remains open on Friday - but its future is uncertain ahead of a debate by Belfast City councillors on Monday night.
Sinn Fein’s Castle Councillor Conor Maskey will bring the motion to council chambers. He claimed as well as being outdated, Belfast Zoo is unsustainable financially.
"Belfast ratepayers subsidise the zoo by approximately £2.5m per year... [which] could be used for far more worthy and much-needed regeneration projects in keeping with the city's modern-day needs."
Sinn Fein has proposed a five-year transition period to return animals to their natural habitat, retain an on-site conservation programme for animals suited to the area and ensure all employees are given the opportunity to retain employment within Belfast City Council.
The SDLP's Carl Whyte hit out at the Sinn Fein move, saying staff had not been consulted.
“The proposal that endangered species, who have rarely or never lived in the wild, can be returned to their ‘natural habitat’ is completely ludicrous and would have consequences which are frankly unthinkable,” he said.
“Belfast Zoo is home to Barbary Lions, a species that is now extinct in the wild so it would be impossible to return these animals to any natural habitat.
“The zoo also is home to some animals who have been rescued from circuses after ill-treatment. Would this proposal see these animals returned to a circus or the wild? Either would be hugely damaging to their welfare.”
Councillor Whyte said national and international breeding programmes have contacted Belfast City Council to express their concern.
“This proposal endangers animals and put jobs at risk. The zoo was constructed in 1974 and requires investment, which can see it once again become a huge tourist attraction,” he said.
Mr Whyte said he would be meeting with council officials to discuss how to safeguard the zoo and restore Floral Hall, the derelict entertainment venue, on its grounds.
Last year, city councillors were briefed on the death of three giraffes at the zoo. One of the animals accidentally strangled itself while feeding and the other two died while undergoing treatment under anaesthetic.
Ulster Unionist councillor Chris McGimpsey called for the attraction to be closed saying it should be turned into a conservation centre.
Last February, a group of chimpanzees escaped from their enclosure at the zoo after making improvised ladders from tree branches.
A zoo spokesperson said any escaped animals were quickly returned to their enclosures.
It came just a month after a red panda named Amber escaped after two electricity fences failed at the zoo. She was eventually found in the Collinbridge area, a mile from the zoo’s grounds.
“There have been alarming incidents recorded recently of avoidable deaths of animals at the zoo,” Mr Maskey added.
“There are increasing instances of other cities taking this more ethical approach to animals. Belfast can and should learn from these examples.
“This has the opportunity to positively transform and develop a prime Belfast City Council owned, north Belfast site, create jobs and promote the city ethically.”
Belfast City Council said it did not comment on motions to be discussed by councillors.