Facebook is under fire for allowing researchers to manipulate users' News Feeds in an undisclosed experiment involving nearly 700,000 users and intended to measure the effects of positive and negative posts on Facebook users' moods.

The Financial Times reports that the United Kingdom's Information Commissioner's Office (ICO) is said to be planning "to ask Facebook questions" after results of the study published in the Proceedings of the National Academy of Sciences solicited widespread outrage from all over the Internet. The ICO reportedly wants to know how much personal data has been compromised in the one-week experiment conducted in 2012 and if users explicitly granted their consent to participate in the study. It will also get in touch with Ireland's data protection authority since Facebook's European headquarters is located in Dublin.

It is unclear what type of violation Facebook might be charged with just yet, but the ICO has the power to impose fines of up to £500,000 and order organizations to change their data policies.

The experiment in question was conducted by a team of researchers from Cornell University and University of California who "manipulated the extent to which people were exposed to emotional expressions on their News Feed." The researchers discovered that, contrary to their earlier hypothesis that positive posts caused a user to feel depressed or left out, Facebook users were more likely to share positive posts in response to seeing positive posts from their friends. Consequently, they are also more likely to make negative posts when exposed to negative posts.

Facebook agrees that it has "communicated poorly" about the study to its users and says it has taken "appropriate measures" to ensure that people's information are protected. The social network also says that "none of the data used was associated with a specific person's Facebook account."

"It's clear that people were upset by this study and we take responsibility for it," writes [subscription required] Facebook's Richard Allan, director of policy in Europe, in a statement. "We want to do better in the future and are improving our process based on this feedback."

Adam Kramer, one of the researchers who conducted the experiment, has posted an apology on his Facebook page. In retrospect, he says the results of the study, which were found to have minimal impact, may not be justified by the furor that the paper has caused recently.

"The goal of all of our research at Facebook is to learn how to provide a better service," Kramer says. "Having written and designed the experiment myself, I can tell you that our goal was never to upset anyone. I can understand why some people have concerns about it, and my coauthors and I are very sorry for the way the paper described the research and any anxiety it caused."