A United Kingdom regulator said it would probe the controversial 2012 Facebook experiment that looked at whether the emotional bent of news feed posts was contagious.

Facebook has come under attack Relevant Products/Services after details of the study were released in recent days. The social network Relevant Products/Services slightly altered which posts some users saw on their feeds, with some seeing happier updates and others seeing more negative ones.

During the study, which lasted just one week, researchers found that the emotional bent of posts did appear to be contagious. Users who saw happier posts were more likely to post positive updates, and users exposed to sadder content were more negative in their posts. The hundreds of thousands of users affected were not notified that they were part of this particular research project.

Britain's Information Commissioner's Office could not be reached by The Times. But according to the Financial Times the data Relevant Products/Services-protection Relevant Products/Services organization wants to know whether its citizens were affected, and whether their data was properly protected.

In a statement, Facebook stopped short of an apology.

"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 company said in a release. "The study was done with appropriate protections for people's information and we are happy to answer any questions regulators may have."

One of the Facebook employees behind the study, however, went further in a post over the weekend, saying that he "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."

The social network has gotten into trouble with American regulators in the past.

After Facebook was accused of telling its users they could keep their information private on its social network, the company repeatedly allowed that information to be shared and made public. Facebook and the Federal Trade Commission came to an agreement in 2012 that the company would improve how it notified users about changes to data privacy; Facebook also agreed to gain users' consent before sharing their information.

Facebook was accused of telling its users they can keep their information private on its social network, the company would repeatedly allow that information to be shared and made public The Federal Trade Commission came to an agreement in 2012 to improve how it notified users about changes to data privacy, and also agreed to gain users' consent before sharing their information.

Critics of Facebook's study have raised the specter that the company could face a class-action lawsuit over the study. According to a report in Forbes, the company added mention of research to its terms of service months after the study was conducted.

Julia Horwitz, a consumer protections counsel at the Electronic Privacy Information Center, said however that other portions of the user agreement could protect Facebook from legal action.

Horwitz, however, said she believes the study may have violated Facebook's agreement with the FTC, which called for better transparency in how user information was being used.