EU regulators investigate Google's plan to buy Fitbit

European Union regulators say they're opening an in-depth investigation into U.S. tech giant Google's plan to buy fitness tracking device maker Fitbit.

The EU's executive commission said Tuesday it's concerned the deal would entrench Google's position in the online ad market by "increasing the already vast amount of data" that the company could use to personalize ads.

EU competition commissioner Margrethe Vestager said the "investigation aims to ensure that control by Google over data collected through wearable devices as a result of the transaction does not distort competition."

Google agreed to buy Fitbit in November for $2.1 billion US. Privacy and consumer groups have called on authorities to block the deal, citing privacy and antitrust concerns.

The EU said that it was concerned the deal would expand Google's "data advantage," and therefore raise barriers for rivals to match Google's online advertising services.

"This deal is about devices, not data," said Rick Osterloh, Google's senior vice-president for devices and services. "We've been clear from the beginning that we will not use Fitbit health and wellness data for Google ads," he wrote in a blog post.

Europe's close examination of tech companies

The investigation underscores the leading role EU authorities have taken in global efforts to regulate the big technology companies.

Vestager has been at the forefront of the movement to rein in the likes of Google and its Silicon Valley rivals.

During her first five-year term as competition commissioner, she slapped Google with nearly $10 billion in penalties for multiple antitrust cases involving its Android operating system, advertising business and shopping service.

Google's plan to acquire Fitbit marked a bold plunge into health and fitness technology for the search behemoth as it tries to become a force in consumer hardware.

Fitbit pioneered wearable fitness technology, with devices that track activities such as running, cycling and swimming and record heart rates and sleep patterns.

The company has more than 28 million active users worldwide and has sold more than 100 million devices.