Two German men who admitted travelling to New Zealand to steal rare native geckos have been jailed.

Dieter Ernst, 56 and Thorsten Richartz, 47, were sentenced to four and a half months jail in the Dunedin District Court after they pleaded guilty to separate charges of hunting protected wildlife and possessing four rare jewelled geckos.

The geckos came from two sites on Otago Peninsula and one site on Banks Peninsula.

It was the longest sentence the men could receive given their guilty pleas, the Department of Conservation said.

Yesterday's sentencing followed an operation involving the Department of Conservation (DOC), Police, NZ Customs Service, the Wildlife Enforcement Group (WEG), and the public.

Judge Stephen Coyle called for the maximum penalty to be increased to deter people from coming to New Zealand and stealing valuable wildlife.

"This is offending against all New Zealanders. I am concerned that some of the jewelled geckos previously stolen from Otago Peninsula and then returned appear to have been re-stolen and are now listed for sale on international websites," he said.

DOC's Otago Conservancy Solicitor Pene Williams said, "Given the current maximum penalty of six months' imprisonment, this was as long as we could expect".

Penalties were under review but this process had not been completed in time to deal with the two men.