"Some people are going to have lots of cats and some people are going to have few. The Government isn't going to limit the number of cats people can own."
Ms Barry was speaking from bird sanctuary Zealandia.
She also said the SPCA's 'spay and release' approach to feral cats was "one of the most foolish and counter-productive techniques and practices I have ever heard."
"I would like the SPCA to stop doing that because if you capture a cat, spay it and release it often what happens is they find a little supermarket for cats, which are the bird sanctuaries."
SPCA head Bob Kerridge told NZ Newswire that was rubbish and the cats were not released near sanctuaries but rather into known colonies which were fed.
Mr Key said he would advise his own cat Moonbeam not to go near the SPCA in case it went ahead with her instructions.
He said he had a good opinion of the SPCA and wife Bronagh had adopted a cat from them in the past and donated to them.
However Moonbeam was not an SPCA cat - she was from a pet shop in Mt Eden.