KIWI egg producers say they are being ordered to phase out battery cages in a "brutally short" time.

The New Zealand Government yesterday announced battery cages would be banned from 2022.

From today, no new battery cages can be installed and Primary Industry Minister David Carter said about 45 per cent will be gone by 2018.

The Egg Producers Federation said the reality was the phase-out has to be completed in four to six years, not 10.

"The formula is, quite frankly, harsh and punitive," EPF chairman Michael Guthrie said.

"The estimated cost starts at $NZ150 million ($A120 million) and goes up from there - a significant number of farmers will quit the industry."

Mr Guthrie said the program simply can't be achieved and Mr Carter will be told that.

About 80 per cent of New Zealand's 42 egg producers use battery cages, and more than one billion eggs are sold each year.

The new welfare code said hens must be kept in larger colony cages, in barns or on free ranges.

Mr Carter said scientific evidence and strong public opinion have made the change necessary.

Mr Guthrie said the industry wanted to stop using battery cages but wasn't being given enough time.

The Green Party said all types of cages should be banned and the welfare code still allows hens to be kept in cruel conditions.