New Zealand Embassy officials moved as quickly as they could to uncover the poison milk scandal in China, Prime Minister Helen Clark says.

Clark on Monday criticised Fonterra over the scandal which has seen contaminated milk powder sold by Sanlu, of which Fonterra has a 43 percent stake, partly responsible for the deaths of at least four children and the hospitalisation of nearly 13,000 others.

New Zealand officials have been criticised for acting too slowly, amid revelations they were first told of the problem on August 14 — almost a month before a full public recall — and took 17 days to pass details on to the New Zealand Government.

Once Clark learned the details on September 5 she took action to alert Chinese central government officials, who ordered the public recall.

Clark defended the embassy, saying the August 14 notification merely consisted of comments by a Fonterra staffer to an embassy official at a social function.

It was not until August 22 that the issue was discussed in a formal meeting with the ambassador, but even then the information was “sketchy”.

From that date the ambassador “vigorously” questioned Fonterra to ensure he had sufficient information to relay the full story to Wellington.

“I think the embassy probably acted as quickly as it could have in light of what it was actually told.”

Clark said Fonterra had been working in a “very difficult context” after local government officials blocked its request for a full public recall in early August, but suggested Fonterra had been slow to pursue alternatives.

Asked if the embassy had been forced to drive that process, Clark said that was her view.

She was also critical of Fonterra in other areas.

“I think a concern that many would share is that Fonterra, in going into a joint venture in China, did not have adequate supply chain management over product that was marketed from its joint venture there.”

It was also slow to respond publicly once the scandal hit the headlines.

“Fonterra really didn’t front for at least three days and then only by videoconference from Singapore which was less than adequate,” she told reporters.

“It knew that this was going to be a big issue and there wasn’t a sign of a proper communications strategy for the New Zealand public.”

Sanlu was the first company identified as selling melamine-contaminated milk powder.

Since then melamine, which causes urinary problems including kidney stones, has been detected in milk products from over 20 companies throughout China.

The scandal stems from the practice of adding the industrial chemical, normally used to make plastics, to watered-down milk to boost apparent protein levels.

Some Chinese press reports have said the scam had been going on for years, with the country’s chaotic and corrupt food safety system unable to detect or prevent it.