The Ministry for Primary Industries is applauding a sharp-eyed worker who spotted three dead baby weasels in a container at a quarantine facility in Hamilton.

Ports manager Sharon Tohovaka says they did the right thing by immediately closing the container of new tyres from Malaysia.

She says even though they were dead - they could have been carrying pests or diseases harmful to this country.

She says if they had arrived alive and managed to get free there would have been greater biosecurity risk.

The find's described as a very unusual biosecurity interception for MPI.