The Abbott government has moved to increase screening of frozen berries from some Chinese factories after the hepatitis A outbreak.

The government said on Tuesday it would enforce tougher measures but it was not immediately clear if the surveillance would only apply to Patties berries, which is believed to be the source of the outbreak.

At least 18 people have been infected with hepatitis A following an outbreak caused by contaminated imported frozen berries. Credit:Getty Images

The move followed days of confusion after Prime Minister Tony Abbott last week suggested the government was already conducting tougher screening, only to have that claim disputed by both the Agriculture Minister Barnaby Joyce and the Agriculture Department in a Senate estimates hearing on Monday.

Mr Joyce and Assistant Health Minister Fiona Nash said on Tuesday 100 per cent screening would apply to frozen berries from factories in China linked to the hepatitis A incident.