The strawberry contamination scare in Australia, which has caused supermarkets to recall brands and farmers to dump fruit, has spread to all six of the country’s states, police have said.

The supermarket chains Coles and Aldi had pulled strawberries from their shelves across Australia except in Western Australia, and on Monday police in that state said a suspected case had been identified there.

A man in the town of York reported to police that he had found a needle in a sink after washing strawberries. The incident came after a seven-year-old girl in South Australia state found a needle in a Western Australia-grown strawberry on Saturday.

A 62-year-old woman was caught putting a needle into a banana in Mackay, central Queensland, in what is believed to have been a copycat act.

Neil Handasyde, president of the Strawberry Growers Association of Western Australia, said growers had received requests from retailers and insurance companies to scan fruit for needles.

“As an industry, we are sure that [the needles] are not coming from the farm, but we’re trying to get confidence into consumers that when they buy … strawberries, that there isn’t going to be anything other than strawberries in there and they’re safe to eat,” he told ABC. “[We] are looking at lots of different ways of tackling this issue. There’s been metal detectors purchased and tamper-proof packaging looked at.”

Handasyde said he had paid AU$20,000 (£11,000) for a metal detector for his berry farm.

New Zealand’s main food distributors, Foodstuffs and Countdown, announced on Monday that they were taking Australian strawberries off their shelves, in a further blow to growers.

Adrian Schultz, the vice-president of the Queensland Strawberry Growers Association, said what had started as a single act of “commercial terrorism” had brought a multimillion-dollar industry to its knees.

“I’m angry for all the associated people – it’s the farmers, the people who supply them, the packaging people, the truckies [truck drivers] – with families to support, who suddenly lose their jobs … it’s far-reaching,” he told ABC radio on MondaySeven brands are believed to have been contaminated, according to police reports. Consumers in Queensland were the first to report finding needles in strawberries. Police in the state, who are leading the investigation, are still unsure whether the sabotage is the work of a single person or several people acting independently.

Ian Stewart, the Queensland police commissioner, said the investigation was complicated by the vast web of supply chains. “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.

The government of Queensland state has offered an AU$100,000 reward for information leading to the arrest of the person or persons responsible.

Growers met the state agriculture minister, Mark Furner on Sunday to discuss the commercial effects of the contamination, which began at a south-east Queensland farm eight days ago.

Queensland, home to about 150 commercial strawberry growers, is a major producer in a national industry worth more than AU$130m a year.

Furner said industry-specific assistance packages were being considered but no plan would be made until an understanding of the “complete effect” of the sabotage was understood.

Jamie Michael, of the Western Australia Strawberry Growers Association, told ABC his farm had dumped strawberries in the peak of the season and that if shoppers stayed away, some growers would not be able to afford to plant a crop for next year.