The Interactive Advertising Bureau, which develops digital advertising standards, and counts Google, Amazon and Facebook among its members, is being sued for “the world’s largest data breach”.

The Irish Council for Civil Liberties is suing the IAB over the user data shared during real-time bidding for advertising space. It argues that most internet users aren’t aware of the breadth of data being shared during this process, nor to whom it is shared.

The suit is being brought by Johnny Ryan, a former advertising industry professional who now works for the Irish Council for Civil Liberties. He argues that, although a user’s identity remains hidden, the sheer volume of data shared constitutes an invasion of privacy.

“Every time we load a page on a commercial website or use an app, the website or app tells tens or hundreds of companies all about us, so that their clients can decide whether to bid on the opportunity to show you an ad,” he says.

“These bid requests include inferences of your sexual orientation, religion, what you’re reading, watching, and listening to, your location.”

The suit was filed in Hamburg on May 18.

“We are reviewing the allegations in conjunction with our legal advisers and will respond in due course, if appropriate,” said a spokeswoman for the IAB, who wasn’t aware of the suit until a BBC journalist contacted them.