A programme to determine the safety of eggs is to be expanded.
In recent weeks, three farms have been stopped from selling eggs because of Salmonella Enteritidis (SE).
New Zealand Food Safety has been carrying out tracing and testing of poultry operations after salmonella was found at an Auckland poultry farm.
It will now widen its focus to 20 egg-laying facilities and five chick rearers, it said.
The producers account for around 80 percent of eggs sold in shops.
NZ Food Safety deputy director-general Vincent Arbuckle said the testing programme is expected to take about two months.
"We've contacted the facilities involved and will work with them to carry out the testing. Where there is evidence that implicates food products, actions will be taken as appropriate, to protect consumers," he said in a statement.
"Consumer safety is our number one priority here. While we think the overall risk to consumers is low, there is developing evidence of a potential link between poultry and recent cases of SE in humans. We consider this testing to be part of our precautionary measures to limit risk to consumers and industry."
Government figures show 47 cases of Salmonella Enteritidis reported in 2021.