The smell of a lab rat is being used to attract the millions of wild rats that are threatening New Zealand's native species.

Auckland-based Massey University Institute of Natural Resources PhD researchers Anna Gsell and Mark Seabrook-Davison have used the smell of caged judas lab rats to attract wild rats.

The experiment could pave the way for a rat-perfumed bait capable of reducing a number of the predators, the researchers said.

The idea was based on the mate searching behaviour of rats in the wild.

The researchers conducted the experiment near private bush on a farm north of Albany.

They recorded trails of paw prints, which was evidence wild rats were coming out of the bush to check out the caged lab rats.

The scientists also used cages without actual rats but containing rat-scented bedding - these also attracted wild rats.

Ms Gsell hoped the positive results of the study would open the way for the commercial creation of a synthetic rat perfume from rat urine to be used in baits and traps.

The Department of Conservation (DOC) have also tested out the experiment.

DOC used the researchers for an emergency rat-catching mission on a pest-free island in the Hauraki Gulf where a rogue rat was seen.

The university's rats were walked on leashes around areas of the island, leaving their scent, the following day the rat was caught 50 metres from where the university's rats were placed in cages.

- NZPA