A European Union privacy watchdog could fine Facebook Inc. as much as $1.63 billion for a data breach announced Friday in which hackers compromised the accounts of more than 50 million users, if regulators find the company violated the bloc’s strict new privacy law.

Ireland’s Data Protection Commission, which is Facebook’s lead privacy regulator in Europe, said Saturday that it has demanded more information from the company about the nature and scale of the breach, including which EU residents might be affected.

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