Threats to contaminate infant formula

Police are appealing for the publics' help following a threat to contaminate infant formula and other formula in an apparent protest over the use of 1080 poison in pest control.

Federated Farmers received anonymous letters in November. Small packages of milk powder, which later tested positive for a concentrated form of 1080, accompanied the letters.

The letters carried a threat to contaminate formula with 1080 unless New Zealand stopped using the poison for pest control by the end of March.

Mike Clement, Police deputy commissioner of National Operations will shortly take questions along with Ministry for Primary Industries deputy director general Scott Gallagher.

Police said the person or people who wrote the letters threatened to make their threat public if the Government did not meet their demand by the end of this month.

Police National Headquarters said a full investigation began in November, with an Auckland-based team called Operation Concord involving up to 36 police staff.

Mike Clement, Police deputy commissioner of national operations, said although it was possible the threat was a hoax, it must be treated seriously. He encouraged the person or group to make themselves known.

"The letter writer may not have really considered the implications of their actions when this communication was drafted," Mr Clement said.

Several specialist groups and support agencies, including MPI, were involved.

Exchange operator NZX said it had placed a trading halt on all dairy futures and options trade and said trading in the shares of three big dairy companies had been put on hold.

Normal futures trading will resume on Wednesday, the exchange said.

Trade in the units of Fonterra and in shares in Synlait Milk and A2 Milk have also been put on a trading halt, the exchange said.