Irish pig meat contaminated with toxic dioxins could have been exported to as many as 25 countries, Ireland's Chief Veterinary Office said on Sunday.
The Irish government has recalled all domestic pork products from shops, restaurants and food processing plants because of contamination with dioxin.
Britain, the main export market, has warned consumers not to eat any Irish pork products after tests revealed the contamination.
"We believe it's in the order of 20-25 countries. It's certainly less than 30," chief veterinary officer Paddy Rogan told a news conference, speaking about how many countries could be affected.
The New Zealand Food Safety Authority said on Monday it is confident the country is safe from contaminated Irish pork, with Customs data showing there had been no imports of pig meat from the United Kingdom in the past 12 months.
Authorities in Ireland said 10 farms in Ireland and a nine in Northern Ireland had used a contaminated pig feed that prompted Dublin to announce the recall on Saturday.
Britain's Food Stands Authority, a government body tasked with protecting public health and consumer interests, said it was investigating whether any contaminated pork products had been distributed in the UK, a major importer of Irish pigmeat.
British supermarket group Asda, owned by US retail giant Wal-Mart, said it was pulling all Irish pork products from its shelves.
The Irish government said on Saturday that laboratory tests of animal feed and pork fat samples confirmed the presence of dioxins, with toxins at 80-200 times the safe limits.
Preliminary evidence indicated the problem was likely to have started in September.
The Irish Association of Pigmeat Processors said the contaminated pig feed came from one supplier and the source had been contained.
In some forms and concentrations, and with long exposure, dioxin can cause cancer and other health problems, but Britain's Food Stands Authority said it did "not believe there is significant risk to UK consumers."
Experts also said the risk to consumers was low. "These compounds take a long time to accumulate in the body, so a relatively short period of exposure would have little impact on the total body burden," said Professor Alan Boobis, toxicologist at Imperial College London.