Australian telecommunications company Optus has been the victim of a hack, with the hacker now backflipping on releasing 10,000 customer records.

The hacker initially demanded one million dollars, or else a tranche of 10,000 records will be released every day over the coming four days.

But within hours the decision was changed.

“Sorry too 10,200 Australian whos data was leaked. Australia will see no gain in fraud, this can be monitored. Maybe for 10,200 Australian but rest of population no. Very sorry to you. Deepest apology to Optus for this. Hope all goes well from this,” the alleged Optus hacker posted to a forum.

The records that have been released so far include names, addresses, email addresses, dates of birth, and gender.

Optus is urging customers to change their passwords and is working with law enforcement to investigate the incident.

A total of 9.8m current and former customers have been impacted by the breach, which the government says is a major corporate failure.

Optus is working with law enforcement and has advised affected customers to change their passwords and online security questions.

This is a developing story and more information will be released as it becomes available.