The Australian competition regulator has accused Amazon of failing to describe its product-search system.

The regulator, the Australian Competition and Consumer Commission (ACCC), confirmed Amazon’s stance in a report published on Thursday.

“Hybrid marketplaces, like other vertically integrated digital platforms, face conflicts of big interest and may act in ways that advantage their products with potentially adverse effects. We have concerns about particular examples of self-preferencing by hybrid marketplaces in Australia, which mirror similar concerns raised by overseas regulators,” ACCC chairman Guns Cass-Gottlieb said.

The ACCC said it surveyed 80 online merchants and that almost half believed large marketplace platforms skewed searches and website presentation to favor in-house products.

According to the report, Amazon did not give the regulator an advantage over its own products, but “the ACCC sought details about inputs of Amazon’s algorithms, which were not provided.”

As a result, “the ACCC does not have information about how Amazon’s algorithms produce search results,” the report said.

The sources for this piece include an article in Reuters.