A Vienna-based privacy campaign group lodged complaints in eight European countries against Elon Musk's X on Monday over "unlawfully" feeding the personal data of users into its artificial intelligence technology without their consent.

The complaints filed by the European Center for Digital Rights -- also known as Noyb ("None of Your Business") -- come after Ireland's Data Protection Commission (DPC) earlier this month took court action against X over its data collection practices to train its AI.

X had recently started "irreversibly feeding" the personal data of more than 60 million European users into its Grok AI technology, "without ever informing them or asking for their consent", according to Noyb.

Noyb slammed X for "never proactively informing" its users that their data is being used for AI training, saying many people appeared to have "found out about the new default setting through a viral post on 26 July".

Last week the DPC -- which acts on behalf of the European Union -- said that X had agreed to suspend its much-criticised processing of users' personal data for its AI technology.

But Noyb founder Max Schrems said in a statement that the DPC failed to "question the legality" of the actual processing, seemingly taking action "around the edges, not at the core of the problem".

Noyb also warned that it remained unclear what happened with already ingested EU data.

Calling for a "full investigation", Noyb has filed complaints in Austria, Belgium, France, Greece, Ireland, Italy, the Netherlands and Spain.

The group has requested an "urgency procedure" against X that allows data protection authorities in the eight European countries to act.

"We want to ensure that Twitter (now X) fully complies with EU law, which -- at a bare minimum -- requires to ask users for consent," Schrems said, referring to the bloc's landmark General Data Protection Regulation (GDPR).

The GDPR aims to make it easier for people to control how companies use their personal information.

The group recently launched similar legal action against social media giant Meta, causing it to halt its AI plans.

Noyb has taken several court proceedings against technology giants, often prompting action from regulatory authorities.

The group began working in 2018 with the advent of the GDPR.