Australia's competition regulator has rejected an undertaking by Alphabet Inc-owned Google that sought to address competition concerns over its planned $US2.1 billion ($A2.8 billion) acquisition of fitness tracker maker Fitbit.
The development comes as Google remains at loggerheads with the Australian government over a number of issues, including proposed laws that will make Australia the first country in the world to force Google and Facebook to pay for news sourced from local media outlets.
In June, the Australian Competition and Consumer Commission voiced concerns over the Fitbit deal, warning Google's acquisition would give it too much of people's data, potentially hurting competition in health and online advertising markets.
Google had sought to address those concerns by offering a court-enforceable undertaking that it would behave in certain ways toward rival wearable manufacturers, not use health data for advertising and, in some circumstances, allow competing businesses access to health and fitness data.
"While we are aware that the European Commission recently accepted a similar undertaking from Google, we are not satisfied that a long-term behavioural undertaking of this type in such a complex and dynamic industry could be effectively monitored and enforced in Australia," ACCC chair Rod Sims said in a statement.
The regulator also noted that several other competition authorities, including the US Department of Justice, were yet to make a decision on the deal.
A Google spokesman said while the company was disappointed with the delay, it will continue to engage with the ACCC to answer their questions.
"We have been working constructively with regulators around the world to close the acquisition of Fitbit and to start building new helpful devices for users," he said.
"As we've said from the beginning, this deal has always been about devices, not data, and we are committed to protecting Fitbit users' privacy."
The ACCC said it would continue its investigation and set a new decision date of March 25, 2021.
The regulator also has inquiries open into advertising technology and mobile app stores, with reports due in January and March, respectively, focusing on the rapidly growing market power of internet giants.