Australian mobile network operator Optus was hit by a lengthy outage earlier today.

It caused transport delays and payment problems, and cut hospital phone lines.

Services have been restored after a 12 hour disruption.

– Getty Images

In total, more than 10 million people were affected, plus thousands of businesses.

Optus have blamed a "technical network fault" for the outage, but given no further details so far.

"The Optus Network has been restored and most services should now be back online. Some customers may need to restart their device or turn flight mode on then off. Some NBN connections may not be restored as yet. We are investigating customer complaints. Please try restarting your modem by turning it off, unplugging it for 30 seconds, and restarting. Our people are doing their best to respond to your concerns, and Optus sincerely apologizes for today’s outage," said the company in its most recent statement on X (formerly Twitter).

Disruption to Optus' network was first reported around 4:00 am local time, and lasted until around 6:00 pm for services to return.

One user on X revealed that her cat had alerted her to the outage, when its automatic WiFi feeder didn't deliver the moggy's meal.