Tough new border restrictions have been imposed by the Ministry for Primary Industries (MPI) to stop contaminated seed from entering New Zealand.
The restrictions follow the discovery of velvet leaf in fodder beet seeds imported from Europe, with a major biosecurity operation underway nationwide to respond to an outbreak of the invasive weed.
MPI said it was still not exactly sure how the contaminated fodder beet seeds entered the country.
But it said the new interim measures would provide another layer of biosecurity until that was known.
The measures included an import ban on all fodder beet seed lines known to be contaminated with velvetleaf.