Pressure is growing to tighten food labelling laws as the number of hepatitis A cases believed to be linked to contaminated frozen berries grew to 13 on Wednesday.

But Prime Minister Tony Abbott appeared to reject a complete overhaul of testing and labelling regulations, saying it was the responsibility of businesses "not to poison their customers".

Mr Abbott said any review of food labels would have to be a "balancing act" that did not impose unnecessary burdens on business.

His comments came as Greens Leader Christine Milne urged the major parties to support a bill that would simplify Australia's country of origin food labels, which both the Greens and consumer groups such as Choice have described as confusing.

The parliament's standing committee on agriculture and industry recommended last year that country of food origin labelling should change.

A Choice survey in 2014 found nearly 90 per cent of Australians were unclear about where their food comes from.

As the first suspected case linked to Nanna's frozen berries was reported in Western Australia, Senator Milne accused the government and Labor of being too influenced by major food companies on the issue.

"Every time that I move on country of origin labelling in the parliament you have the big corporations, the supermarkets, the global food and beverage giants out there saying to the other parties don't pass it," she said.

"[It's] not to do with the legislation, it's to do with the big end of town wanting to hide from the Australian community the information that people need in order to be able to buy a product."

Mr Abbott said in a radio interview on Wednesday that any changes to labelling would require a "balancing act" so as not to hurt businesses.

"The last thing I want to do is put a whole lot of additional requirements on business that will make their life very, very difficult and which will raise unreasonably prices to consumers," Mr Abbott told the ABC.

The Prime Minister said he supported Food Standards Australia New Zealand considering whether tougher screening requirements were necessary for berries from overseas.

Labor's agriculture spokesman Joel Fitzgibbon said the government could do more to restore public confidence by moving "immediately to change the risk classification for these frozen fruit and vegetables".

The Greens bill proposes simpler country of origin labels that put foods into one of three categories.

The words "product of" or "grown in" would be used for items that are wholly grown and processed in one country.

"Manufactured in" would be used to describe food that has been substantially transformed in a particular country.

Senator Milne said this would replace the term "made in" on food labels because too many consumers thought "made in" was a reference to where the ingredients were grown.

The term "packaged in" would describe goods that were highly processed but couldn't claim to have been significantly processed or taken their ingredients from a particular country.

It is unclear if either of the major parties will support the Greens bill.

Agriculture Minister Barnaby Joyce is in favour of strengthening country of origin rules.

But if the issue finds support within cabinet, Mr Joyce appears more likely to pursue changes by putting his own proposal in the government's forthcoming agricultural competitiveness white paper.

"That will take discussion with industry and consumer groups and with other parties – including the Greens and [independent senator] Nick Xenophon," a spokesman said.

Mr Fitzgibbon agreed labelling was important, but said in this instance "the package clearly declared it to be Chinese product" and other measures were more urgent.

He said the spate of hepatitis A cases highlighted the government's "reckless" decision to abolish the role of the inspector general of biosecurity.

"Tony Abbott is going on about red tape but there are some circumstances where regulation is very important when we're dealing with human health," Mr Fitzgibbon said.

Late Wednesday, a government spokesman rejected a suggestion the Abbott government was abolishing the role of Inspector General of Biosecurity.

AUSTRALIA'S CURRENT COUNTRY OF ORIGIN LABELS

"Product of" or "Grown in" Each significant ingredient originated in a particular country and most of the production occurred there.

"Made In" The product was made in a particular country and at least 50 per cent of the cost to produce the product was incurred in that country.

If a food product says "Made in Australia" it does not necessarily mean the ingredients were grown in Australia.

IN A NUTSHELL

• Country of origin labelling is required on unpackaged goods including fresh and processed fruit, vegetables, nuts, spices, herbs, fish and meat
• The country of origin of the food must be identified, or a company can state the food is a mix of local and imported food or a mix of imported foods
• Packaged food must identify where the food was made, produced or grown or where it was manufactured or packaged
• It must identify if the food is a mix of local and imported ingredients or a mix of imported foods

Some foods include claims on their labels such as "Proudly Australian owned" or "100% Australian owned". These statements are about the ownership of the company and do not indicate where the product was made or where its ingredients came from.

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