SYDNEY/BENGALURU (Reuters) – Australia’s antitrust regulator warned Google’s planned $2.1 billion acquisition of fitness tracker maker Fitbit (FIT.N) may give it too much of people’s data, potentially hurting competition in health and online advertising markets.

The Australian Competition and Consumer Commission (ACCC) is the first regulator to voice concerns about the deal in a preliminary decision on Thursday. The Alphabet Inc (GOOGL.O)-owned tech giant is already at loggerheads with the Australian government over planned new rules about how internet companies use personal information.

“Buying Fitbit will allow Google to build an even more comprehensive set of user data, further cementing its position and raising barriers to entry to potential rivals,” ACCC Chairman Rod Sims said on Thursday. “User data available to Google has made it so valuable to advertisers that it faces only limited competition.”

The ACCC, which does not generally have the power to block a deal outside Australia, will announce its final decision on August 13. In previous takeovers, it has ordered certain conditions such as asset sales.

Google wants the deal, announced in November, to help it compete with Apple (AAPL.O) and Samsung (005930.KS) in the market for fitness trackers and smart watches.

But consumer groups have raised privacy concerns. The U.S. Justice Department is evaluating the deal, while the European Commission is due to give a ruling in July.

Following an ACCC report last year, the Australian government is working on new rules to force large internet companies to disclose their data usage, and pay for the local media content. Google and Facebook Inc (FB.O) oppose most of the proposed changes.

Google said it had promised not to use Fitbit data for advertisements, and to give users choice and control over their data.

“We will be transparent about the data we collect and why – and we do not sell personal information to anyone,” Google said in an email.

Fitbit was not immediately available for comment.