A warning has been issued about frozen berries, which have been linked to three cases of Hepatitis A.

New Zealand Food Safety says there is not sufficient information on a specific brand to initiate a targeted product recall.

But there have been three cases in people who regularly eat frozen berries. Those with chronic liver damage, the elderly and pregnant people are being told to be especially careful if eating frozen berries.

The advice is to briefly boil frozen berries before eating them, or ensure cooking temperatures exceed 85degC for one minute. And wash your hands before eating and preparing food.

Food Safety says its working with frozen berry suppliers to ensure they are aware of potential risks and are actively managing the issue.