Ireland's data regulator on Monday slapped Facebook owner Meta with a €265 million ($277 million) fine after details of more than half a billion users were published online.

The penalty resulted from an investigation, started in April 2021, after data including names, phone numbers and email addresses of users were leaked on a hacking website in 2019.

The Data Protection Commission ordered Meta to make a range of corrective measures to prevent a similar leak from happening again. The company said it patched the vulnerability in 2019 after the leaks were confirmed.

Facebook fines in Ireland

It is the fourth time the commission has fined one of Meta's companies, bringing the total to almost €1 billion.

In September, the watchdog hit its Instagram subsidiary with a record fine of €405 million, which Meta was appealing in the high court.

Last year, the watchdog fined WhatsApp €225 million for violating rules on sharing people's data

The fines are part of the wider enforcement of the General Data Protection Regulation.

The Irish regulator said it has 40 inquiries open in technology giants, including another 13 involving Meta.

Ireland is the home of the regional headquarters of a number of major tech players — including Apple, Facebook, Google and Twitter.