In a week that has seen the social network company’s chief operating officer, Sheryl Sandberg, make a half-hearted apology over its psychological research experiment on 700,000 users’ news feeds — and caused much debate among academics and the research community over the rights and wrongs of the study — the story continues to rumble on.

On Wednesday, Sheryl Sandberg told the Wall Street Journal the study had been poorly communicated but fell short of a full apology. “This was part of ongoing research companies do to test different products, and that was what it was; it was poorly communicated. And for that communication we apologise,” she said.

However, in its complaint, EPIC accused Facebook of “purposefully messing with people’s minds” before stating that: “At the time of the experiment, Facebook did not state in the Data Use Policy that user data would be used for research purposes. Facebook also failed to inform users that their personal information would be shared with researchers. Moreover, at the time of the experiment, Facebook was subject to a consent order with the Federal Trade Commission which required the company to obtain users’ affirmative express consent prior to sharing user information with third parties.”

EPIC said that Facebook’s “secretive and non-consensual use of personal information” for research purposes was conducted with researchers at Cornell University and the University of California, San Francisco, “who failed to follow standard ethical protocols for human subject research”.

This followed the news that in the UK, the Information Commissioner’s Office (ICO) is to investigate whether Facebook broke data protection laws when it allowed researchers to conduct the experiment on unknowing users.