A potato virus which affects potatoes used to make chips has been found for the first time in New Zealand.

The potato mop-top virus, known as PMTV, has been found in tubers from two properties in the Canterbury region.

David Yard of Biosecurity New Zealand, says PMTV was not a food safety issue but, if it became widespread, could cause productivity issues for growers.

PMTV is common in other countries, he says.

Affected potatoes can display symptoms including distortions to the skin, deep cracking, and rust coloured arcs, streaks or flecks in the tuber flesh.

Biosecurity New Zealand is investigating how the virus entered the country.