Internet users are being urged to change their passwords on all accounts, in the wake of a major data breach at Yahoo.

The company says details from over half a billion user accounts were compromised, in what is the biggest hack in recorded history.

Although the data breach took place in late 2014, Yahoo says it was only uncovered by a recent investigation and first disclosed it last night.

The stolen information includes names, email addresses, telephone numbers, dates of birth, and encrypted passwords. It also includes the answers to usual security questions, not all of which are encrypted.

The Data Protection Commissioner here says it's seeking further information about the exact nature of the breach and the details involved.

The hack has also led communications minister Denis Naughten to reveal he's preparing new laws to improve cybersecurity in Ireland.

Our political correspondent Gavan Reilly reports: