Renfe, Spain’s national railway company, disclosed Friday that it had suffered a cybersecurity breach that allowed attackers to access some customer information.

The company said the incident originated on servers operated by Adif, the state railway infrastructure manager, which had previously been compromised and were connected to Renfe’s systems.

According to Renfe, the information accessed by the attackers was limited primarily to customer names and email addresses. The company said there is currently no conclusive evidence that the stolen information was made public.

Renfe also said there was no evidence that hackers accessed customers’ banking or financial information, payment methods, identification documents or other particularly sensitive data.

The railway operator said the breach followed several weeks of attempted cyberattacks. Renfe said those earlier attempts had been detected and successfully blocked, while rail services continued operating normally.

Spanish newspaper El Mundo reported that investigators believe a criminal organization may have used a system resembling artificial intelligence technology developed by Anthropic to target Adif’s website.

The report described the incident as potentially the first AI-assisted cyberattack against the website of a Spanish public company. The attack reportedly lasted several days, and Adif’s website was unavailable Friday evening.

El Mundo cited sources close to the investigation in describing the suspected use of AI. Renfe did not publicly confirm that artificial intelligence was used in the attack.

Spanish media also reported that approximately 500 gigabytes of data may have been taken during the incident. La Razon cited sources familiar with the investigation who said the method of attack appeared to point toward a foreign-based group.

Renfe has not disclosed how many users were affected or when the breach occurred.

The incident comes amid growing concerns over the use of increasingly capable artificial intelligence systems in cyberattacks. Security officials and technology companies have warned that advanced AI tools can potentially make sophisticated hacking operations faster and more accessible.

The breach also highlights broader concerns about cyberattacks against critical infrastructure as European countries face heightened security risks amid Russia’s ongoing war in Ukraine