The competition watchdog has raised concerns about the way Aldi, Coles and Woolworths treat suppliers when dumping products from their supermarket shelves.
Australian Competition and Consumer Commission chairman Rod Sims says that in some cases, the supermarket giants have failed to give reasonable notice before delisting products.
"The worst examples were delistings that appear to have occurred on the same day as the notice was served," Mr Sims told the Australian Food and Grocery Council's forum in Canberra on Tuesday.
"Some delist notices did not include any real reasons for delisting and where reasons were provided, they were typically very general in nature."
Mr Sims said the ACCC has raised these concerns with the big three supermarkets following recent compliance checks and expects them to address the issues quickly.
He said supermarkets need to improve the way they notify suppliers when delisting products to avoid breaching the Food and Grocery Code of Conduct.
Under the code, which came into effect on July 1, supermarkets can only delist a supplier's product for genuine commercial reasons and must give reasonable written notice.
Supermarkets must also inform the supplier of their right to have decisions reviewed by a senior buyer.
