Former foreign minister Julie Bishop has defended her stewardship of one of Australia's most prestigious universities amid allegations of bullying and widespread dissatisfaction on campus.

Ms Bishop fronted a Senate estimates hearing in Canberra, making an in-person appearance after a scheduling change, to face serious questioning by her former colleagues.

"We have been through a tumultuous time, possibly unprecedented, for the Australian National University and change and restructuring can be hard and can be painful for some in our community," she told senators on Friday.

"Like many universities across Australia and globally, the ANU is facing financial, operational and organisational challenges."

Among the challenges have been explosive bullying allegations levelled at Ms Bishop at a

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