Authorities are no closer to saying if the threat to poison baby formula with 1080 was a hoax, or who wrote the blackmail threats - even though police said today their investigation had ballooned to absorb more than 30 staff.
Members of the public concerned with possible infant formula product tampering, such as possible pinpricks in packaging lids, have contacted police.
Police expect a result within 24 hours after sending the suspect infant formula tin for more tests following the threat.
"We have got one tip that needs examining," Police commissioner Mike Bush said this afternoon. "On initial blush it looks like a malfunction through manufacture, but we want to be absolutely sure, so that we can reassure the public about the safety of the product."
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Assistant Commissioner Malcolm Burgess said 30-40 people were now working on Operation Concord, up from 20-25 at the start of the investigation.
"Inquiries by their nature become bigger and you put more people into them," Mr Burgess said.
Mr Bush and Mr Burgess said neither the Ministry for Primary Industries (MPI) or any other agencies had put pressure on police to "ramp up" the investigation.
Police said Detective Superintendent Andy Lovelock joined Concord as lead investigator a few weeks ago.
Mr Burgess said he was confident in the abilities of all the senior officers involved in Concord from its inception.
He said initially "a range of investigators" were involved in the inquiry in response to being asked who had overall command prior to Mr Lovelock joining the team.
Police would not rule out whether an individual, group, or even a state or corporate actor was behind the threats.
Asked if he was frustrated with the lack of a police breakthrough, MPI deputy director-general Scott Gallacher said today his priority was simply the "health and well-being" of New Zealanders.
"Throughout this...I have very much welcomed working with the police. They are devoting significant resources to this."
Mr Gallacher said he was happy with how police were prioritising staff and resources, and with the level of contact between MPI and police.
Letters with a lethal dose of 1080 powder were sent to Fonterra and Federated Farmers in November.
The letters contained a threat to contaminate infant and other formula with 1080 if the poison, used to kill invasive pests, was not banned by the end of this month.
Mr Gallacher said MPI had for a long time been looking at possible alternatives to the use of 1080.
"Even before this criminal blackmail threat was raised, we were always working with all stakeholders to explore long-term opportunities for long-term pest management."
Information hotlines
If you have any questions about what to feed your baby, call Plunketline 0800 933 922 or Healthline 0800 611 116
For more information go to foodprotection.govt.nz