Labour's food safety and primary industry spokesperson is critical of the way the Government has shrugged off the high rejection rate for dairy products sent to China.
A Chinese consumer website said New Zealand topped a list of countries that had their milk products rejected by China in the past year.
It said customs data showed 60 batches of New Zealand product were rejected between October 2013 and November 2014, nearly 14 percent of the total.
The site did not specify the reasons, but the Ministry for Primary Industries said in New Zealand's case, it would more likely be technical errors than food safety problems.
Primary Industries Minister Nathan Guy has said the figures would not be a great surprise, because New Zealand was the world's largest dairy exporter and China purchased a third of the country's dairy exports.
However, Labour's spokesperson, Damien O'Connor, said the Government should not be dismissing the issue in that way.
"I'm concerned that the Minister has shown a rather flippant attitude. Sixty batches from New Zealand; we have no idea why they were rejected and when farmers are trying harder to produce better quality milk and we're told that we must meet higher standards internationally, it's really important that we know why such batches were rejected.
Whether it was technical, whether it was paperwork or indeed, related to some residue, it's essential that MPI and the Minister find out more about this and let the farmers know, because our reputation in the international market place for producing fine and safe food must be upheld."
Last year, more than half of the dairy products imported by China came from New Zealand.