EUROPEAN UNION ANTITRUST officials have started questioning rival firms about Facebook’s purchase of WhatsApp for $19 billion.

Questionnaires have been sent to a number of major technology and online messaging companies, asking about the merger’s impact on the competition and their markets, The Wall Street Journal reports.

The process, which deals with how firms control and user personal data when they offer services, comes before a formal merger review that will provide the first in-depth looks at the app economy and social media through competition law.

The EU wasn’t originally going to review Facebook’s WhatsApp deal since the app didn’t have sufficient revenue in the region to trigger its merger law. However, Facebook used a provision of the EU law to ask for the commission to conduct a single review that would cover the 28 nations in May, instead of facing separate ones in three or more EU countries.

That provision allowed the EU to begin reviewing the deal last month. The telecoms industry in Europe have been lobbying against the merger, arguing that services like WhatsApp use their infrastructure, but aren’t taxed or regulated in the same way.

Personal data and privacy haven’t played a major role in competition reviews, but some regulators and privacy advocates have said this is likely to change, according to the Wall Street Journal.

Read: Ford recalls 100,000 vehicles in North America over safety concerns >

Read: This device reads out printed text to the blind in real-time >