Optus data breach: who is affected, what has been taken and what should you do?

Optus customers’ private information may be compromised after a cyber-attack hit the Australian phone and internet provider. Photograph: Bianca de Marchi/AAP

Australia’s second-largest telco, Optus, has suffered a massive data breach, with the personal information of potentially millions of customers compromised by a malicious cyber-attack.

It is believed the attackers were working for a criminal or state-sponsored organisation.