FORTUNE — Facebook Inc. FB has approached the European Commission to review its proposed $19 billion deal to buy messaging service WhatsApp, the Wall Street Journal reported Wednesday, citing people familiar with the matter.

The deal — the biggest acquisition of a startup in years — has already been approved by the Federal Trade Commission, but getting approval in Europe may prove politically tricky, as the authorities have taken an increasingly dim view of US tech giants’ approach to issues ranging from privacy to tax affairs.

The Commission, which polices anti-trust matters in the 28-country EU, declined to comment. The WSJ said however, that the Commission had notified national anti-trust authorities of Facebook’s request.

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The WSJ cited Thomas Graf, an antitrust lawyer with Cleary, Gottlieb, Steen & Hamilton in Brussels, as saying that “Facebook might prefer to go to the Commission than go before several national regulators, which would each ask it for information.”

Normally, the Commission wouldn’t intervene in a deal where the target company has such a small presence in the EU market. However, Europe’s big telecom companies are concerned that the deal would hit their services for messaging text and pictures, because of Facebook’s dominance of the social media scene.

National regulators tend to be more sympathetic to the concerns of their local champions in such cases, and are also more exposed to pressure from their respective national governments. The criteria for reviewing a deal also differ from country to country, another thing that could make the process more difficult for Facebook.