Several brands have been recalled, while a major New Zealand grocer said that it had stopped selling imported strawberries as a precaution.
The contamination was first reported in Queensland, where the government is offering a $100,000 reward (almost $72,000 in USA dollars) for information.
He directed Food Standards to investigate whether there are supply chain weaknesses that need to be fixed.
'At the end of the day, the job is very, very clear.
Australian police are investigating claims that needle sabotage has now spread to six brands of strawberries across five states.
Cases of fruit tampering were first reported in Queensland last week, before spreading to New South Wales, Victoria, the Australian Capital Territory, South Australia and Tasmania.
The contaminated strawberries came from Mal's Black Label, a West Australian brand that has now been pulled from shelves.
Dr Harris said it was hard to speculate on the reason why people would target the strawberry industry.
Foodstuffs and Countdown, food distributors in New Zealand, have suspended selling Australian strawberries.
Australia's Department of Health ordered a review into the handling of strawberries after fruit containing sewing needles was found in supermarkets across Australia.
He urged consumers to be vigilant - but added that strawberries are safe to eat after washing and chopping.
The crisis has spiraled since a man was hospitalized after swallowing a needle that was hidden inside a strawberry in Queensland over a week ago.
"There is a range of really complex scenarios which could play out here, and we're looking at all of them, and that's what's taking the time", he said on Monday.
Industry body the Strawberry Growers Association blamed a disgruntled ex-employee for those incidents, but Queensland police say they have yet to identify a suspect and are "keeping a very open mind" as they seek to interview more than 100 people involved in the supply chain.
The Strawberry Growers Association of Western Australia has warned that without support, "the industry will be forced to abandon their crops or continue dumping fruit and we may not have a strawberry industry next year", according to the West Australian site.
Berry Licious, Berry Obsession and Donnybrook branded strawberries, all Queensland brands, remain off the shelves at some supermarkets with Coles pulling all strawberries off their shelves except in Western Australia.