Local berry growers are worried a hepatitis A scare linked to imported fruit could accidentally put people off local produce.

Twelve cases of hepatitis A prompted Foodstuffs to recall some Pams frozen berry products while government food safety specialist investigated into the source of the illness.

Earlier this week, Ministry for Primary Industries said frozen Serbian berries were under investigation because of a possible link. Read more here.

Deputy general of New Zealand food safety Vincent Arbuckle says eight of the 12 cases are linked by genetic sequencing, meaning they are likely exposed to the same source of the virus.

Local producers are worried consumers may not pick up on the difference between locally-produced fresh and frozen products and those imported from overseas.

Northland berry grower Patrick Malley told Checkpoint consumers should have confidence in locally grown fresh and frozen products.

Waikato's Sunrise Berries managing director Todd Feather reassures consumers that New Zealand's food safety is of a high standard.

He says berry plants can pick up diseases through bad farming practices, but care is taken to ensure that doesn't happen here.

Feather says his staff monitor the crop everyday and regular tests are carried out to detect harsh pathogens.

Although New Zealand produces its own berries, most are eaten fresh, while the frozen supply comes in from overseas.

Malley says there is a need to import berries from overseas because of the cost difference.

"It's cheaper to grow berries [that are frozen] over in Serbia, than it is for us grow fresh berries and have some of them go into the frozen market. And that's just the nature of things."

Feather says berries imported from Chile, China and Eastern Europe can be sold in the frozen market due to their low labour costs.

New Zealand Food Safety says tracing the illness back to specific products is a challenging process, especially as hepatitis A has a long incubation period of up to 50 days.

People are being warned to continue cooking frozen imported berries as a precaution, while the investigation continues.

Foodstuffs spokesperson says customers who have already bought the berries should boil them or return them to the store to get a full refund.

-RNZ.