Alexandra Craig says the two cat shelters where she volunteers are swamped with strays after Canberra was overrun with kittens in spring. She says kittens are being given away or sold for $30-$60 on Facebook, with no undertaking by the potential buyer to have them desexed or even microchipped or vaccinated.

Prominent Australian conservationists have co-signed a letter from former ACT chief minister Jon Stanhope urging the ACT government to bring forward a cat containment declaration for Canberra.

But Territory and Municipal Services Minister Shane Rattenbury wants more advice. Mr Rattenbury said anecdotal evidence indicated high compliance for containment in newer suburbs among the first generation of residents but compliance declined when the next generation moved in.

"TAMS and the Conservation Council have recently done a joint program to raise awareness in the cat containment suburbs about people's obligations to improve the effectiveness," he said.

Retrofitting the policy to existing areas of Canberra would require a long lead-in time.

"The experts have suggested to me something like 10 years would be appropriate, that way for some people their cats would no longer be with us… people who were getting new cats would know the policy was coming, and people would have time to build a cat run or enclosure," he said.

Mr Rattenbury said he would also consider cat registration and better education campaigns to protect wildlife from marauding cats.

Ms Craig supports containment. "But if they actually want it to work, they have to be practical and put some funding behind it in the way of cat desexing. It is pretty much impossible to keep an un-desexed cat inside - they yowl to be let out and their owners can't bear it," Ms Craig said.

"I know of an un-desexed cat that busted open a screen window to escape." Ms Craig said veterinary fees could be as much as $400 for desexing a female cat. Males required a simpler procedure and were not as expensive.

"We are at a disadvantage in Canberra of not having local councils. They often put on cheap desexing days where the procedure only costs $20-$30."

Ms Craig is running "Canberra Cat Fix", a project to help people on low incomes to desex their cats. So far the fundraising websites, www,facebook.com/CanberraCatFix and www.gofundme.com/CanberraCatFix have raised $2000.

"If we can reach our target of $6000 we will be able to desex just under 50 cats. While this doesn't sound like a lot, it will potentially prevent thousands of kittens from being born when you take into consideration the cycle of one cat having five kittens, then each of those kittens having five kittens, and so on. "

ACT Animal Rescue spokeswoman Andrea Henningsen said containment prevented cats from roaming, being hit by cars and getting into fights. The rescue service re-homes cats and charges an adoption fee which covers the cost of a health check, desexing, vaccination, worming and microchipping.

Meanwhile the Australian Veterinary Association's ACT division says it encourages containment, after it was approached by the Conservation Council.

"Cats contained to an owner's property should have access to an outdoor escape-proof enclosure to provide activity and stimulation. These enclosures should not be electrified," the association said.

"Ideally, cats should be trained to be contained early i.e. as young kittens. Young kittens that are raised with the owner's boundary are less likely to suffer behavioural stress."