Facebook's plans to integrate the messaging functions of Instagram, WhatsApp and Messenger could be blocked in the EU by the region's privacy laws.
The Irish Data Protection Commission (DPC) said in a statement Monday that "ultimately the proposed integration can only occur in the EU if it is capable of meeting all of the requirements of the GDPR."
The Irish commission supervises Facebook at an EU level as the tech giant's European headquarters are in Dublin. It said in the statement that it had asked Facebook Ireland for an "urgent briefing" on the proposals to merge the three services.
Europe's General Data Protection Regulation (GDPR) legislation protects individuals' personal data from being kept or shared without consent. Organizations can face penalties of up to 20 million euros ($22.87 million) or 4 percent of their annual global turnover for breaching the rules.
The New York Times reported on Friday that Facebook was planning to integrate its messaging services, claiming that Chief Executive Mark Zuckerberg was personally behind the move. Each service would remain a standalone app, but messages would be able to be sent between the three — bringing together more than 2.6 billion users, according to The Times.
"(We) will be very closely scrutinizing Facebook's plans as they develop, particularly insofar as they involve the sharing and merging of personal data between different Facebook companies," the Irish DPC said.
"Previous proposals to share data between Facebook companies have given rise to significant data protection concerns and the Irish DPC will be seeking early assurances that all such concerns will be fully taken into account by Facebook in further developing this proposal."
Facebook declined to comment when contacted by CNBC.
The tech giant has faced a series of backlashes over the sharing of users' personal information.
In December, the Washington, D.C. attorney general said it would sue Facebook over the Cambridge Analytica scandal, claiming in a lawsuit that the company misled users and improperly collected their information without making them aware. It came after the U.K. Information Commissioner's Office (ICO) fined the company £500,000 ($662,900) over the scandal in July.
In March 2018 — before GDPR came into effect — a plan to share data between WhatsApp and Facebook was ruled as illegal by the U.K. Information Commissioner's Office (ICO).
At the time, the ICO said it had investigated whether WhatsApp could legally share user data with Facebook, finding that "such sharing would involve the processing of personal data for a purpose that is incompatible with the purpose for which such data was obtained."
The European Commission also fined the tech giant 110 million euros ($122 million) in 2017 for giving "misleading information" about its acquisition of WhatsApp. Facebook bought Instagram in 2012 and WhatsApp in 2014.
On Friday, Zuckerberg penned an op-ed in the Wall Street Journal, defending his company and hitting out at "misreported" claims that the social network sells user data.