WELLINGTON, New Zealand (AP) — Police on Tuesday filed blackmail charges against a man they say threatened to poison supplies of infant formula in a case authorities worried could have led to wider fallout for the country's lucrative dairy industry.

Police Commissioner Mike Bush told media they had arrested a 60-year-old Auckland businessman and charged him with two counts of blackmail following a large investigation that involved 35 staff and cost several million dollars.

"It reflects how seriously we view crimes of this nature," Bush said.

The arrest came after dairy exporter Fonterra and advocacy group Federated Farmers said they received letters in November that threatened to lace infant formula with sodium fluoroacetate, a poison commonly called 1080, unless conservation authorities stopped using it to kill rodents and other pests by March.

The threats prompted health authorities and manufacturers to carry out tens of thousands of tests on products to make sure nobody had tampered with them. Nothing was found amiss and Bush said Tuesday the man posed no further risk to the public.

Police declined to name the man ahead of a scheduled court appearance. Should he be found guilty, he would face a maximum sentence of 14 years in prison on each charge.

Fonterra, the world's largest exporter of dairy products, thanked police and health authorities for an "exhaustive" investigation.

"Fonterra is pleased to hear that an arrest has been made," said Chief Executive Theo Spierings in a statement.

Prime Minister John Key told reporters the arrest was good news in a case that had worried the government "immensely" despite the likelihood it was a hoax.

In the year ended June, the South Pacific nation sold 12 billion New Zealand dollars ($7.6 billion) worth of dairy products to overseas markets, making them the nation's single largest export.

Consumers in China and other countries pay a premium for New Zealand milk powder because it's considered of high quality. Exporters and officials worry that any hint of contamination could affect sales.