Margrethe Vestager, the European Commission's top antitrust official, had long warned
a probe of the giant online retailer was coming. It's the latest regulatory broadside against the growing power of big tech companies on both sides of the Atlantic.
In a statement
on Wednesday, Vestager said e-commerce had boosted choice for consumers and reduced prices.
"We need to ensure that large online platforms don't eliminate these benefits through anti-competitive behavior," Vestager said. "I have therefore decided to take a very close look at Amazon's business practices and its dual role as marketplace and retailer, to assess its compliance with EU competition rules."
The Commission will investigate standard agreements between Amazon (AMZN)
and the sellers, and whether the seller data is used by Amazon unfairly. It will also look into the selection of the "Buy Box" on Amazon's search results.
It's not clear how long the probe will take.
In a statement, Amazon said: "We will cooperate fully with the European Commission and continue working hard to support businesses of all sizes and help them grow."
The European Union has emerged as a key battleground for tech companies because of its tough rules on data protection, hate speech, taxation and competition issues.
In March, the bloc hit Google with a third antitrust fine
, ordering it to pay €1.5 billion ($1.7 billion) for abusing its dominant position in online search advertising.
and Facebook (FB)
have also been penalized by European regulators. In March, Spotify asked the bloc's antitrust regulators
to intervene in a dispute with Apple over its App Store.
Meanwhile, pressure on tech companies is building in the United States.
Amazon, Facebook and Google (GOOGL) faced lawmakers
in Washington this week, answering questions about their market dominance and reports of anti-competitive tactics.
The US Federal Trade Commission is reportedly preparing to fine Facebook roughly $5 billion for mishandling user data. Meanwhile, the US Justice Department is laying the foundation
for a potential antitrust investigation of Google.