A 60-year-old businessman from Auckland has been arrested and faces charges of blackmail over alleged threats to contaminate infant milk formula with 1080 poison.

The arrest was announced by Police Commissioner Mike Bush today, with the man set to appear in Manukau District Court on two charges of attempting to commit blackmail.

The threat to contaminate infant formula with 1080 poison was revealed in March this year. Photo: New Zealand Government Food Protection.

Fonterra and Federated Farmers both received blackmail threats last year from someone demanding an end to the use of 1080 poison to control pests, including possums.

Neither organisation use the poison, but it is widely used to control pests on Department of Conversation land.

Fonterra Chief Executive Theo Spiering says the company is pleased to hear that an arrest has been made as part of the investigation into the criminal blackmail threat made public in March this year.

Theo says: 'We would like to thank the Ministry for Primary Industries and New Zealand Police for their continued and exhaustive efforts on behalf of the New Zealand dairy industry, retailers and the general public.

'We'd also like to acknowledge the significant joint industry response to this threat.”

Following the threat, infant formula was removed from supermarket shelves to avoid the risk of contamination, although it was still available for sale and MPI and other agencies assured parents it was safe to use.

The scare hit Fonterra hard, with international markets reacting adversely to the news.

Police today say they think the arrested man acted alone.

The investigation into the threats was one of the biggest carried out by police in recent years, costing more than $3 million and involving 35 full time staff.

More than 2600 people were considered as part of the investigation, named Operation Concord, with over 60 'significant persons of interest” approached for interviews.