Comedian Mike King, who used to front a campaign promoting pork products, says the "callous and evil" practice of crate farming pigs should be outlawed immediately.
King said that after breaking into a pig farm with animal activists where pigs were kept in crates, he was deeply ashamed he took part in promoting the type of farming, TVNZ's Sunday programme reported.
"If I had known this was going on I would never have supported this. I firmly believe that anyone who sees this would say this has to stop."
The farm was filmed by animal rights group Open Rescue and footage shown to Agriculture Minister David Carter, who said he wasn't aware of the extent to which pigs were confined.
It was a bit disturbing to see them in such conditions but he said he needed to know if the footage showed what was typical of the pork industry and he suspected it was not.
Animal rights group Save Animals from Exploitation's director Hans Kriek said such cage farming was widespread.
The pigs were touching the sides of the 60cm wide and 2m long cages and couldn't turn around.
Some pigs could live for up to five years in a cage, he said.
About 45 percent of New Zealand's sows, or 22,000, were kept in crates and the law was giving legal protection to farmers to be cruel to animals, Mr Kriek said.