Australia's consumer watchdog says it is being flooded with complaints that some retailers are hiking up the cost of COVID-19 Rapid Antigen Tests.

The Australian Competition and Consumer Commission (ACCC) today said it had "significant concerns" over the pricing of the tests, which it has seen as extreme as $500 for two tests.

The watchdog said it is receiving on average around 150 reports from consumers a day about the pricing of Rapid Antigen tests – or RATs – as state governments push residents towards DIY testing to ease pressure on PCR test clinics.

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"At the extreme end, we have received reports or seen media coverage of tests costing up to $500 for two tests through online marketplaces, and over $70 per test through convenience stores, service stations and independent supermarkets, which is clearly outrageous," ACCC Chair Rod Sims said.

"There are several businesses that have repeatedly come to our notice thanks to the information provided by the public.

"We are asking those businesses to urgently explain the prices they are charging."

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Mr Sims said the ACCC had contacted more than 40 test suppliers, major retailers and pharmacy chains seeking information about their costs and current pricing.

Wholesale prices for a single rapid antigen test currently vary between $3.95 and $11.45, subject to Supply Chain variables such as the size of the order placed and who manufactures the tests.

"The supply chain is often complex, with several businesses involved from the initial supply to the retail sale of tests to consumers. Retailers operating under the same brand or chain may be setting prices and selling tests independently of the other stores in the chain," Mr Sims said.

"This means the wholesale and resulting retail prices can vary significantly."

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Of particular concern are the pricing strategies used at convenience stores and petrol stations, which make up the bulk of consumer-led complaints.

"We are looking in particular at reports of single tests being sold at around $30 or above from certain stores," Mr Sims said.

The most commonly complained about retail price in the watchdog's reports is around $20 for a single test.

"In the middle of a significant outbreak of COVID-19 in a pandemic, the excessive pricing of rapid antigen tests required to diagnose the illness and protect other members of the public, is of significant concern to the ACCC," Mr Sims said.

"Only a few weeks ago tests were readily available at most chemists and supermarkets for around $10 for a single test.

"We realise demand and supply chain issues have impacted since then, but our initial research suggests that a price of around $20 per test or more, however packaged, may be hard to justify based on the average wholesale costs and such retailers should explain why the price is so high."

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Under Australian Consumer Law, businesses and suppliers can largely set their own prices but they may not make false or misleading statements about the reasons for those prices.

In specific circumstances, excessive pricing of a product deemed to be essential may come under the legal definition of "unconscionable conduct".

A Biosecurity Act which came into force on 8 January 2022 and will remain in place until 17 February 2022 prohibits a person from reselling, or offering to resell, rapid antigen tests bought at retail level for mark-ups above 20 per cent.