The federal government has contradicted claims by Patties Food that there is no link between its Nanna’s brand frozen mixed berries and a national hepatitis A outbreak.

Assistant Health Minister Fiona Nash said on Thursday there was very strong evidence consumption of the product led to an increased risk of developing the infection.

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Although food testing was an unreliable way to detect the virus, the Victorian Health Department had confirmed evidence trace levels from a sealed packet of the product.

Hepatitis A virus was also detected in an open packet of Nanna’s one kilogram fresh frozen mixed berries from a case, she said.

Agriculture Minister Barnaby Joyce said the company intends to reintroduce Nannas and Creative Gourmet brands to the marketplace using berries sourced from new farms and factories with stricter microbiological testing.

He said berry products from Chinese factories and farms associated with the recall are all still being held at the border.

All imported product that was linked to the outbreak, was recalled by Patties and will never be put back onto the market, he said.