By Foo Yun Chee

BRUSSELS (Reuters) - Austrian advocacy group NOYB will seek an injunction against Meta Platforms, it said on Wednesday, that could lead to substantial claims if the tech giant goes ahead with plans to use Europeans' personal data to train its AI models.

NOYB, or none of your business, led by privacy activist Max Schrems, said it had sent a cease and desist letter on Wednesday to Meta, which plans to start using personal data from European users of Instagram and Facebook from May 27.

Meta has cited legitimate interest under EU privacy rules for using users' data to train and develop its generative AI models and other AI tools that can be shared with third parties.

The U.S. tech giant said last month users would receive a link to a form that allows them to object to their data being used for training purposes and that private messages and public data from accounts of users under the age of 18 will not be used.

Schrems criticised Meta's rationale.

"The European Court of Justice has already held that Meta cannot claim a 'legitimate interest' in targeting users with advertising. How should it have a 'legitimate interest' to suck up all data for AI training?" he said in a statement.

"We are currently evaluating our options to file injunctions, but there is also the option for a subsequent class action for non-material damages. If you think about the more than 400 million European Meta users who could all demand damages of just 500 euros or so, you can do the math," Schrems said.

NOYB said an injunction could be filed under the EU Collective Redress, which enables consumers to pursue collective lawsuits against companies in the bloc. It set a May 21 deadline for Meta to respond.

Meta rejected NOYB's arguments, saying its approach complies with guidance from the European Data Protection Board and follows discussions with the Irish privacy enforcer.

"NOYB's arguments are wrong on the facts and the law," a Meta spokesperson said.

"We've provided EU users with a clear way to object to their data being used for training AI at Meta, notifying them via email and in-app notifications that they can object at any time."

NOYB, which last year urged EU privacy enforcers to act, said Meta could give users an option to opt-in rather than opt-out and also provide clear conditions for AI training, such as using anonymised user data, in line with EU privacy rules.

(Reporting by Foo Yun Chee; Editing by Susan Fenton and Barbara Lewis)