In a statement issued by Singtel, the parent company of Optus, Bayer Rosmarin said it was an appropriate time for her to make an exit.

Optus suffered a nation-wide outage on 8 November, with its mobile and broadband services out of commission from 4am until 6pm.

In the statement, Bayer Rosmarin said: "On Friday I had the opportunity to appear before the Senate to expand on the cause of the network outage and how Optus recovered and responded.

"I was also able to communicate Optus’ commitment to restore trust and continue to serve customers. Having now had time for some personal reflection, I have come to the decision that my resignation is in the best interest of Optus moving forward.

“It’s been an honour and privilege to lead the team at Optus and to serve our customers. I am proud of the team’s many achievements, and grateful for the support of the Optus team, Moon, and the Group. I wish everyone and the company every success in the future.”

Singtel Group chief executive Yuen Kuan Moon said: “Optus appointed Kelly at the beginning of the pandemic, and we acknowledge her leadership, commitment and hard work throughout what has been a challenging period and thank her for her dedication and service to Optus.

“Kelly has always led with integrity and had all stakeholders’ best interests at heart. We understand her decision and wish her the very best in her future endeavours.”

This is the second major incident over which Bayer Rosmarin has presided. Last year, Optus was hit by a network attack, with access to the company's network being gained through a publicly accessible API.

Michael Venter, the chief financial officer, will function as interim chief executive until a new chief is appointed.

Yuen also said that veteran global telecommunications executive and former Optus Business managing director Peter Kaliaropoulos would join the comapny on 22 November in the newly created position of chief operating officer, reporting to the interim chief executive.