Facebook may be subject to investigations by European data protection groups following revelations that it manipulated the news feeds of nearly 700,000 users.

The social media giant admitted altering the news feeds of 689,000 users to show specific emotional expressions, as part of a data research experiment conducted over a week in January 2012. The revelations have generated outrage as Facebook did not inform users it was altering their feeds. The company says users give permission for research when they create a Facebook account.

But despite this claim, European privacy watchdogs are now attempting to determine whether Facebook has broken any privacy laws.

Ireland’s Office of the Data Protection Commissioner, which regulates Facebook’s operations outside of North America, said in a statement: “This office has been in contact with Facebook in relation to the privacy issues, including consent, of this research. We are awaiting a comprehensive response on issues raised.”

The Information Commissioner’s Office of Britain stated: “We’re aware of this issue and will be speaking to Facebook, as well as liaising with the Irish data protection authority, to learn more about the circumstances.”

The Federal Trade Commission, which regulates Facebook in the United States, has not said if it will pursue similar avenues of enquiry.

Facebook told TIME that none of its activities should concern regulators in Europe. “None of the data used was associated with a specific person’s Facebook account. We do research to improve our services and to make the content people see on Facebook as relevant and engaging as possible,” a spokeperson said.

“It’s clear that people were upset by this study and we take responsibility for it. We want to do better in the future and are improving our process based on this feedback. The study was done with appropriate protections for people’s information and we are happy to answer any questions regulators may have.”

It is not yet known where the targeted users lived. However, approximately one in every 2,500 users at the time of the experiment would have had their news feeds altered.

Contact us at letters@time.com.