At a news conference in Beijing, McCully tried to allay fears about the quality of New Zealand's milk products after 42 tons of milk powder were quarantined by Chinese officials, New Zealand's TVNZ reported Thursday.
Fonterra, the producer of the powder, has been repeatedly embarrassed in recent months by shipments of its products caught up in Chinese food standards.
The bacteria that can cause botulism was found in its supply chain. Fonterra announced Wednesday milk powder exported to China in May was found to have elevated nitrate levels.
China ordered a recall this month of lactoferrin made by a rival New Zealand company for the same reasons, the state-run Xinhua news agency reported.
While saying the timing of revelations about the milk power was "not perfect given the current issues," McCully said "it's not an embarrassment given it's not a public health issue in any shape or form."
Wang said Chinese authorities "must adopt a serious attitude" toward problems with the Kiwi milk products because they "relate to the health and interests of Chinese consumers," Xinhua said.