Brussels announced a probe Thursday into efforts by the retail industry to stop shoppers using websites outside their own countries, in the latest step towards a single digital market across the EU.
EU Competition Commissioner Margarethe Vestager said she expected to complete a general investigation by mid-2016, adding that it could lead to later cases against specific companies.
In the EU's crosshairs are the cross-border "geoblocking" barriers that often prevent consumers from seeking cheaper prices abroad online, or which stop them using services such as the BBC iPlayer or Netflix when they travel.
"I, for one, cannot understand why I can watch my favourite Danish channels on my tablet in Copenhagen -- a service I paid for -- but I can't when I'm in Brussels," said Vestager, a former economy minister.
"Think of a French tourist who buys a pair of Italian shoes in Rome. Why is she re-routed to a French website when she tries to buy them online from home?" Vestager said in a speech in Berlin.
The investigation due to start in May will be the latest in a series of anti-trust investigations by the European Commission, the powerful executive branch of the 28-nation European Union.
Internet giants Amazon and Google are among those targeted by previous competition probes, which have exposed deep divisions between Washington and Brussels on trade regulation.
- 'Barriers' for customers -
For Brussels the issue at stake is the extension of the single market that has been the EU's raison d'etre since its formation more than 50 years ago to the digital era.
Europe as a bloc is the world's biggest economy, but despite its 500 million potential consumers it largely remains a divided continent of 28 distinct economies, especially when it comes to media and the Internet.
Although half of all EU consumers shopped online last year, for products ranging from hotels and car hire to books and DVDs, only 15 percent bought from sellers based in other member states, the EU said.
Across the EU, digital services like music streaming site Spotify or shopping behemoth Amazon, often remain confined to national borders, with separate accounts required from one country to another.
Vestager, who has taken a hard line on anti-trust cases just six months into the job, said the probe would "focus on the barriers to the cross-border sale of goods and digital content erected by private companies."
Consumers would benefit from a wider choice and lower prices, she said.
The probe will seek information from every EU country with questionnaires sent to holders of content rights, broadcasters, manufacturers, merchants of goods sold online as well as firms that offer price comparisons online.
- 340-bn-euro benefits -
The European Commission did not name any firms in relation to the new probe but said there were "indications that some companies may be taking measures to restrict cross-border e-commerce."
After the initial general probe is completed next year the Commission could then take on specific cases of "restrictive business practices and abuse of dominant market positions", it said.
Vestager said a single digital market could add 340 billion euros ($372 billion) to EU gross domestic product and make Europe more competitive abroad at a time when the economic recovery is still sluggish.
She acknowledged that language barriers and different national laws make it difficult for consumers to shop abroad.
"But often it's the companies themselves that undermine cross-border trade by erecting technical barriers such as geo-blocking," she said.
The announcement of the probe came a day after Andrus Ansip, the European Commission's vice president for the digital single market, unveiled an ambitious plan to overhaul the bloc's digital landscape.
"Let us do away with all those fences and walls that block us online," said Ansip, the former prime minister of Estonia, one of the world's most electronically connected nations.