June 8 (Reuters) - Australia's antitrust regulator has filed a lawsuit against Airbnb Inc (ABNB.O), accusing the accommodation-sharing website of misleading users into paying more than advertised for their stays, widening its scrutiny of global technology platforms.

From 2018 to 2021, the San Francisco-based internet giant advertised and charged room rates in United States dollars without indicating the much higher figures in Australian dollars, the Australian Competition and Consumer Commission (ACCC) said in a court filing that it made public on Wednesday.

Advertisement · Scroll to continue 
Airbnb refused to refund users who complained about being misled, saying they had chosen to view rates in U.S. dollars even though users said they had not, the ACCC said in the filing. Airbnb also refused to refund currency conversion fees, claiming they were banks' responsibility, the regulator added.

"While a fraction of a percentage of guests are believed to have been impacted ... we will compensate affected guests," Susan Wheeldon, Airbnb's country manager for Australia and New Zealand said in statement to Reuters.

Advertisement · Scroll to continue 
Airbnb declined to offer further details about compensation.

Wheeldon said Airbnb has since updated its platform so relevant currencies are "clearly displayed" from the first page for Australian guests.

The lawsuit puts Airbnb in the company of several high-profile targets of a regulator bent on reining in the power of big technology firms. Last year, its actions led to Meta Platforms Inc's (FB.O) Facebook and Alphabet Inc's (GOOGL.O) Google paying media outlets content licensing fees.

Advertisement · Scroll to continue 
It is currently conducting a review of Amazon.com Inc (AMZN.O) and other online retailers that may recommend changes to the sector.

In the Airbnb lawsuit, the ACCC said users "were deprived of the opportunity to make an informed decision about whether and at what price to book accommodation."

They "suffered further harm in the form of price difference costs and, in at least some cases, transaction fee costs," the regulator said, without giving dollar amounts.

Airbnb stood to benefit unfairly over competitors because the "false and misleadingly low prices conveyed ... made the accommodation available on the platform appear to be more attractive," the ACCC said.

The ACCC said it is seeking an unspecified fine and court orders for Airbnb to compensate affected customers. In a statement, it said thousands of people had complained to Airbnb about the difference in advertised prices and amounts charged.

The Australian dollar bought an average of 72 U.S. cents during the time covered by the lawsuit, meaning a customer renting accommodation advertised at $500 would actually pay around A$700 plus foreign exchange fees, the regulator said.