BRUSSELS – The European Union is considering creating a powerful new regulator to oversee a swath of mainly U.S.-based Internet platforms, according to an internal policy document that lays bare the deep concerns in top EU policy circles around the threat posed by companies like Google Inc. and Facebook Inc.

Such a move would be the biggest hurdle yet for U.S. Internet firms operating in Europe, many of which are already facing investigations and lawsuits over issues ranging from unfair competition to tax avoidance, The Wall Street Journal reported.

The document, prepared in February by senior officials for the EU?s Digital Commissioner G�nther Oettinger and seen by The Wall Street Journal, is a long way from becoming policy. Its analysis would need to be converted into proposals by the European Commission?the EU?s executive arm?and approved by national governments and the European Parliament.

But it offers a long-term blueprint for the regulation of Europe?s digital sector that goes far beyond a general plan for the region due to be announced next month, which calls only for a ?comprehensive investigation? into the role of Internet platforms.

The February paper warns that some online platforms?such as search engines, online marketplaces and social networks??are transforming into super-nodes that can be of systemic importance for the rest of the economy.?

?Only a very limited part of the economy will not depend on them in the near future,? it says. It lists 32 examples of such platforms, all but five of which are U.S.-based, and only one based in Europe?Swedish music-streaming service Spotify AB.

The paper warns that a lack of transparency around how these platforms operate allows them ?to exploit asymmetric positions on the market at the expense of other market operators and consumers,? potentially putting ?the whole European economy at risk.?

?Evidence of negative effects [of platforms] in business-to-business relations and in particular on SMEs is?growing,? it says.

The answer, according to the paper, is a new ?supervision framework? that would govern the relations between Internet platforms and other businesses. These could include a ban on ?unfair? practices such as price-parity clauses?agreements which prevent a seller using a platform from offering a better price elsewhere?and a requirement that platform operators don?t discriminate between their own services and those of third parties.

Overseeing the new rules would be a central ?EU-wide body? with the power to request information from platform operators around the way they collect and use data, and to intervene in disputes between operators and the businesses using their platform, according to the paper.