The head of Australian telecoms firm Optus said Friday she was "deeply sorry" for an outage that cut mobile and internet services to more than 10 million people.

A technical glitch in the early hours of November 8 crashed Optus systems for nearly 12 hours.

The fault interrupted communications for a large proportion of the Australian population, also disrupting electronic payments, emergency services lines and access to government services.

"It is indisputable that on that day our performance was not acceptable. We let you down and for that I am deeply sorry," Optus chief executive Kelly Bayer Rosmarin told a Senate committee hearing into the outage.

Unable to pinpoint the exact cause more than six hours after the outage began, Optus had to perform a hard reset of its system, she said, describing it as "a brute force resuscitation of the network".

But the head of Australia's second-largest telecoms provider deflected questions about a media report she was considering stepping down over the failure.

The Australia Financial Review said she could leave as early as next week, citing sources close to the chief executive speaking on condition of anonymity.

"My focus is on the team, the customers, the community. My focus is not on myself," Bayer Rosmarin told the Senate committee.

When pressed by the panel to deny or confirm the report, the chief executive said she had not read any reports in the morning because she had been preparing for the hearing.

Optus says its routers automatically disconnected after becoming overloaded during a scheduled software upgrade.

"The reality is that our network should have coped with this change, but on this occasion, it did not," Bayer Rosmarin said.

She agreed with a statement by Optus parent Singtel that the software upgrade itself was not the "root cause" of the outage.