The Australian antitrust regulator on Thursday kicked off an inquiry into the local units of Amazon.com Inc, eBay Inc and other online markets to ensure fairness in a sector where sales have soared through the coronavirus pandemic.

The Australian Competition and Consumer Commission (ACCC), which previously slapped the world's toughest content licencing rules on internet giants Facebook Inc and Alphabet Inc's Google, called for industry submissions.

"Online marketplaces are an important and growing segment of the economy so it is important that we understand how online marketplaces operate and whether they are working effectively for consumers and businesses," ACCC Chair Rod Sims said in a statement. "We want to be sure that the rules that apply to traditional retail are also complied with in the online context."

The ACCC inquiry will take submissions until mid-August with a final report due in March 2022. Local representatives of Amazon and eBay were not immediately available for comment.

The ACCC will examine the relationships between large online markets and third-party sellers and shoppers, including competition impacts and handling of data, complaints and reviews.

Amazon has not reached the market dominance in Australia since launching in 2017 that it experiences elsewhere, but still doubled sales in calendar 2020, the ACCC said.

Overall, Australian online purchases jumped 57 percent in 2020 for a record USD 50.5 billion spend amid a series of coronavirus lockdowns, the regulator added.

The ACCC said it had received wide-ranging complaints, including the "quality of goods sold on marketplaces, the timeliness of payment remittance to sellers, how goods are put on display on marketplaces, and the level of support provided by marketplaces to consumers when disputes arise".

The ACCC has been conducting a series of investigations in recent months as part of a broader Digital Platform Services Inquiry.