BRUSSELS—European privacy regulators on Friday fired a warning shot to Facebook Inc.'s WhatsApp and Yahoo Inc., saying they sent letters to the companies expressing concerns about possible violations of the bloc's data-protection rules.

A European Union body representing national data-protection authorities from the bloc's 28 states said it sent WhatsApp a letter expressing "serious concerns" about the messaging service's new terms that allow it to share user information including phone numbers with its parent, Facebook. The regulators urged the company to pause the data sharing until "legal protections" could be assured.

In a letter to Yahoo, the regulators outlined concerns about a 2014 data breach the company announced in September, as well as allegations that the company built a system that scanned customers' incoming emails at the request of U.S. intelligence services, the body said. Yahoo has denied such a system exists.

The regulators said they demanded more information from the companies on the issues, in a first step that could lead to national data-protection authorities to open up their own probes and eventually fine the companies if they find they violated the bloc's privacy rules.

A German privacy watchdog has already demanded that Facebook stop collecting WhatsApp user data—an order Facebook said it would appeal.

In response to the EU privacy regulators' move, a WhatsApp spokeswoman said: "We're working with data protection authorities to address their questions." She added that the company reached out to the regulators for feedback before the policy change. A Yahoo spokesperson wasn't immediately reached for comment.

For Facebook, which has also come under fire for the new terms from U.S. consumer privacy advocates groups, the pushback from European regulators opens a new front in Facebook's privacy battles.

Germany's Federal Cartel Office earlier this year said it was investigating whether Facebook abuses its dominance as a social network to harvest personal information. France's privacy watchdog has threatened to fine Facebook if it doesn't change how it handles data about its users.

Facebook has said it is confident it complies with European data-protection law.

The EU privacy authorities on Friday said that because WhatsApp's policy change includes conditions that didn't exist when current users signed up, that raises concerns about the validity of the user's consent as well as the rights of non-WhatsApp users.

For Yahoo, the regulators noted that "a great number of EU accounts" were stolen when hackers penetrated Yahoo's network in late 2014 and stole personal data on more than 500 million users.

The company should notify concerned users about the possible consequences and "cooperate with all upcoming national data protection authority's inquiries and/or investigations," the body said.

Write to Natalia Drozdiak at natalia.drozdiak@wsj.com

 

(END) Dow Jones Newswires

October 28, 2016 06:05 ET (10:05 GMT)

Copyright (c) 2016 Dow Jones & Company, Inc.
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