SYDNEY, Sept 29, 2025 (BSS/AFP) - Australian telecommunications giant Optus said Monday it had suffered a network outage that prevented calls to emergency services, just over a week after a similar interruption of service linked to four deaths.

Optus -- one of Australia's top telecoms providers -- said the outage on Sunday impacted thousands of people in New South Wales and lasted more than nine hours.

The firm said it had "confirmed with police that all callers who attempted to contact emergency services are OK."

"Optus continues to investigate the cause," it added.

This month Optus said it suffered an outage that impacted 600 people across South Australia, Western Australia and the Northern Territory for at least 10 hours.

The outage prevented calls to emergency services, with four deaths now linked to the outage.

Australia's finance minister Katy Gallagher told national broadcaster ABC that news of Sunday's outage was "more disappointing news off the back of the major disruption that happened the week before".

"I think there's questions that Optus are going to have to answer about what happened in the last fortnight and their response to it," she said.

Last week, Optus announced details of an independent review that will probe the series of events that took place and determine why emergency calls did not connect.

The firm was also last week fined $66 million for selling products to vulnerable customers between 2019 and 2023 that they did not need or want, leaving many in debt.

Federal Court Justice Patrick O'Sullivan labelled the company's conduct as "extremely serious" and "appalling".