South Australia's education chief has called for a national inquiry into how coloured play sand contaminated with asbestos was imported into the country.

The number of sites that have reported stocking the product has climbed to more than 450 in South Australia, according to an updated post on the SA Education Department's website.

"I want to know how this stuff got through our borders, how it ended up on the shelves of major retailers like Kmart and Target and then ended up in schools, preschools and thousands of households," Education Minister Blair Boyer said on Wednesday.

Mr Boyer said he had written to the federal government asking for an inquiry and hoped other jurisdictions would join him in the request.

"What are the checks that occur with products like this?" Mr Boyer said.

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