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 with 30 staff on the case.

Police are testing infant formula after a number of tins were found with pin-pricks in packaging lids.

Dairy companies are confident security measures at their facilities are tight enough to prevent a 1080 contamination.

New Zealand shares rose yesterday, heading back towards a record high after a two-day slide.