SYDNEY, July 22 (Reuters) - The Australian antitrust regulator on Thursday began an inquiry into the local units of Amazon.com Inc, (AMZN.O) eBay Inc (EBAY.O) 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 Facebook Inc and Alphabet Inc"s (GOOGL.O) Google, said it was now looking at retail as part of a wider examination of so-called Big Tech. read more "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 would take submissions until mid-August with a final report due in March 2022, the regulator said. An Amazon spokesperson said the company looked "forward to engaging with the ACCC on these important topics in the coming months", while an eBay representative was not immediately available for comment. The Australian regulator said it would 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% in 2020 for a record $50.5 billion spend amid a series of coronavirus lockdowns, it 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. ($1 = 1.3609 Australian dollars)