Westland Milk Products says a small amount of lactoferrin powder with elevated nitrate levels has been exported to China.
It says the powder has been traced and quarantined, and doesn't present a food safety risk.
Labour's primary industries spokesman, Damien O'Connor, says the timing is terrible.
"It comes just weeks after contaminated baby formula made in New Zealand created international headlines nu skin product," he said on Monday.
"This is a reminder for every dairy company and food exporter that the eyes of the world are looking closely at New Zealand's products."
Mr O'Connor says the public needs assurances that products are being tested to the highest standards and that accuracy is beyond challenge nuskin group.
"Once again the self-regulation model needs to be reassessed and government certification backed up by close government oversight of all our food production systems."
The Ministry for Primary Industries revoked export certificates for four consignments of lactoferrin made by Westland after unacceptable levels of nitrate were found in two batches.
The company says early investigations have shown cleaning products which contain nitrates were not adequately flushed from the plant prior to a new production run nu skin hong kong.