The European Commission (EC) is set to carry out a wide-ranging review of the role of some of the world's biggest online companies as it considers tighter regulation.
The months-long inquiry will delve into issues of transparency of search results and pricing, data use, promotion of services and relationships between companies.
It is part of the EC's Digital Market Strategy, unveiled on May 6. The paper sets out a number of policy proposals designed to boost economic growth by reducing national barriers for online services.
The EU last month announced an antitrust suit against Google relating to allegations it abused its market domination in online search to promote its own products over those of rivals.
Brussels is set to investigate the behaviour of some the biggest US companies which have established a presence in the European market. The review is not expected to result in legal challenges against the firms, rather it is more likely to lead to tighter regulation of the market.
The EC also announced a separate competition probe into the e-commerce sector that could eventually lead to legal challenges in the future, although there is not a short-term threat of legal action.
"Europe has strengths to build on, but also homework to do, in particular to make sure its industries adapt, and its citizens make full use of the potential of new digital services and goods," said Guenther Oettinger, EU Commissioner for Digital Economy and Security.
Streaming across the EU
Meanwhile, the EC will review internet catch-up services and national copyright laws, in an attempt to reduce barriers to accessing services across the bloc.
"The Commission wants to ensure that users who buy films, music or articles at home can also enjoy them while travelling across Europe," the EC said in a statement.
There would also be a "review of the Satellite and Cable Directive to assess if its scope needs to be enlarged to broadcasters' online transmissions and to explore how to boost cross-border access to broadcasters' services in Europe," it said.
Such a move could mean UK residents may be able to use catch-up services like iPlayer in France or Germany in the future.