Ireland’s data privacy watchdog said on Friday it’s investigating Elon Musk’s social media platform X over its use of personal data to train his artificial intelligence chatbot Grok.

The Data Protection Commission said it has opened an inquiry into “the processing of personal data comprised in publicly-accessible posts” that European users posted on X.

“The purpose of this inquiry is to determine whether this personal data was lawfully processed in order to train the Grok LLMs” under the bloc’s data privacy law, the commission said in a statement posted online.

An LLM, or a large language model, is a vast pool of text including articles, blog posts, essays and other material scraped from online sources that is used to teach the algorithms underpinning generative AI systems.

Under the 27-nation EU’s stringent data privacy law, known as the General Data Protection Regulation, or GDPR, the Irish watchdog acts as the lead regulator for X because its European headquarters is based in Dublin.

The watchdog has the power to impose penalties of up to €20 million ($36 million) or 4 per cent of a company’s total annual revenue for severe violations.

X did not respond to an email request for comment.