Biosecurity officials are investigating the discovery of genetically-modified plants in the open air at the Plant and Food Research campus at Lincoln University.
It is the second time this year MAF Biosecurity has had to look into a breach involving the science company.
Two Arabidopsis plants were discovered outside a glasshouse on the campus.
The plant, a common weed known as rockcress, is often used in genetic engineering trials because of its readiness to receive genetic modification.
MAF Biosecurity says it is not yet clear who the plants belong to.
Plant and Food Research says there is evidence they have come from a third party.