Releasing wild cats back on to rural properties to manage pests in Queenstown has been called a "disaster" by Predator Free New Zealand.
QT Community Cats - which provides rescue, adoption and rehoming services for cats - is trialling a programme where wild cats are trapped, desexed and released on rural properties to manage rabbit and rodent populations.
Its trustee secretary Mel Gold said the aim was to help prevent a boom of feral cat breeding, while using cats to control other pests.
However, the programme has been met with criticism and concerns about the impact it could have on native wildlife.
Predator Free New Zealand general manager Jessi Morgan called the programme "misguided".
She said that cats had a major impact on endangered and native species, which Otago is home to many of, including birds and lizards.
"There seems to be a misunderstanding about the predator-prey relationship. It will really impact the local biodiversity."
Cats could also spread the protozoan parasite Toxoplasma gondii, which causes toxoplasmosis, to sheep.
The infection can cause reproduction issues.
"[The programme] is a bit of a disaster all round, to be honest."
Morgan said having no clear guidelines for cat management, regionally of nationally, was also a part of the problem.
She wanted the group to stop the programme, and advise the owners of any rehomed cats to keep them at home.
Otago Regional Council environmental implementation manager Andrea Howard said the council had received two inquiries, as well as about seven messages on social media, about the programme.
The council had no regulatory authority over pest control methods, but there were concerns.
Grand and Otago skink populations were at critically low levels in Central Otago, mainly due to cat predation, she said.
"Feral cats have a major impact on New Zealand's native and non-native species.
"They feed on rabbits, birds and bird eggs, rats, hares, bats, lizards, mice, weta and other insects."
Rules concerning feral cats were in place for site-led programmes on the Otago Peninsula, West Harbour-Mt Cargill and Quarantine and Goat Islands.
But there were no rules for the management of feral cats outside of those three areas, Howard said.
QT Community Cats did not respond to requests to comment on the criticism.