The Government is immediately stepping up the amount of independent domestic testing on dairy products in a bid to try and reassure trading partners.
The announcement followed a second incident of contaminated New Zealand product being detected in a key export market - and suggestions the domestic testing regime may be too lax.
Westland Milk co-operative said on Monday that Chinese testing had detected elevated nitrate levels in lactoferrin powder it had exported.
While the nitrate levels were well above the maximum allowed - Westland and the Government say the product wasn't a threat to health.
Westland blamed a failure in its cleaning processes at its plant for the incident.
Ealier this month, Fonterra blamed a dirty pipe at its Hautapu plant in Waikato after tests in Australia revealed it had sold product tainted with bacteria that can cause botulism.
Food Safety Minister Nikki Kaye said the Ministry for Primary Industries informed her on Monday it's increasing its testing.
Ms Kaye said the government inquiry into the Fonterra botulism scare will look into the country's testing regime.
The Infant Milk Formula Council is publicly questioning whether the merging of the Food Safety Authority into the Ministry for Primary Industries led to a less rigorous standard of testing.