The "crass use of power" by university managers was one of the main threats to academic freedom in South Africa today, physicist Nithaya Chetty said on Wednesday.

Delivering the University of Cape Town's annual TB Davie lecture, he said universities needed to return to democratic values.

Managers increasingly found it convenient to foist change on their institutions "in autocratic ways".

"The crass use of power trumps intellectual discourse as political rhetoric and populist beliefs are increasingly holding sway within our universities," he said.

Chetty, who currently teaches at the University of Pretoria, resigned from the University of KwaZulu-Natal last year following a clash with the administration on the issue of academic freedom.

He is also president of the South African Institute of Physics.

Chetty said academic freedom appeared to be viewed by a growing number of university managers, and by some politicians, as "a distraction, a kind of irritation that is barely tolerated".

Even some academics and students were dismissing the importance of academic freedom in the face of competing priorities.

"Especially now that academic freedom is increasingly under threat in South Africa, I feel that ordinary academics like ourselves need to stand together and fight for our common cause for an intellectually freer university system in South Africa," he said.

Academic freedom was however not a special privilege accorded to academics, but a responsibility and obligation to be critically engaged with society.

Being public critical voices was part of academics' job and their contract with society.

Chetty said he could understand why an academic might be disciplined for vandalism showing up drunk for work, but he could not fathom the need for charging somebody for what they said.

Within the limits set by the Constitution, no thought or utterance should be banned from a university, no matter how repugnant that view might be.