Five people have been arrested near Hokitika on the West Coast after a protest against a 1080 operation on Tuesday.

Police were called to the farm south of Hokitika, where a helicopter drop of the pest poison had been about to start.

They say nails had been laid on the road, puncturing the tyres of a police car and a private security car.

A group of about 20 protestors had also gone through a cordon and were near the helicopters.

Four men and one woman have been charged with offences under the Trespass Act and the Bio-Security Act.

The aerial operation eventually got under way.

Federated Farmers game and pest management spokesman Donald Aubrey said the protesters' actions were "absolutely unacceptable" and he was glad the police were called.

Mr. Aubrey said the protesters had recently threatened a Federated Farmers member, and also threatened to poison their stock.