Alphabet (GOOGL -4.44%) (GOOG -4.50%) subsidiary Google will face a full-scale antitrust investigation by the European Union (EU) into its attempt to acquire fitness tracker Fitbit (FIT) for $2.1 billion, according to a report by Reuters.

In order to appease the EU and get the deal done, Google had offered to forego using the fitness data it collected from the devices to target ads to users. It appears that wasn't enough to allay antitrust concerns.

A gavel near a laptop with wrapped stacks of $100 bills on the keyboard next to a scale.

Image source: Getty Images.

The EU's Competition Commission was already conducting a preliminary review of the acquisition, which is scheduled to be completed on Aug. 4. When it finishes its initial evaluation, the commission plans to launch a more comprehensive investigation, which is expected to take as long as four months.

Regulators and privacy advocates alike are concerned that Google could not only increase its stranglehold on internet search with the move, but will also gain access to a wealth of health data, on top of its existing treasure trove of personal information.

Google announced back in November that it planned to buy Fitbit in a bid to better compete with Apple (AAPL -0.74%) and Samsung, which command considerable chunks of the smartwatch and fitness tracking markets, leaving Google out in the cold.

Earlier this month, the company said it wouldn't use the health data Fitbit gathers from users for targeted advertising. "This deal is about devices, not data. We appreciate the opportunity to work with the European Commission on an approach that safeguards consumers' expectations that Fitbit device data won't be used for advertising," a Google spokesperson said in a statement.