THEY are illegal to keep as pets in NSW but sugar gliders are becoming the pet of choice in Britain, vying with dogs and cats to be domestic companions.

The nocturnal mammals may be native to the Australian bush but their cute looks, compact size and gliding ability have endeared them to a growing number of Britons, The Daily Mail says.

Another report has the creatures retailing at up to £150 ($330).

It is illegal to keep most native animals as pets in NSW, with the exception of dingoes, spinifex-hopping mice and plains rats.

National Parks and Wildlife Service wildlife management officer Geoff Ross said sugar gliders did not make good pets.

"They're not easy to maintain - they require a higher level of maintenance than your average cat or dog," he said.

Sugar gliders should be kept in outdoor aviary-type enclosures.

Mr Ross said there were also ecological reasons for not keeping the animals in the family home.

Their reintroduction into the wild, accidental or otherwise, could introduce diseases into the local population. It could also introduce genetic changes, which would threaten the tiny mammals' future.

"Could you imagine the impact of this species if it was released in North America, for instance, into the Everglades?" he said.

"It is a highly adaptive species."