Witnesses say a student has been whisked away by unknown people for protesting during a University of Zimbabwe graduation ceremony featuring President Robert Mugabe.

An Associated Press photographer covering Thursday's event says the graduating student held a placard complaining about joblessness in the country.

Such stunts have become common at graduation ceremonies at this southern African country's oldest university.

Unverified pictures circulated on social media with a student holding up a placard during the ceremony. Police said they were unaware of the incident. Activists flooded social media calling for the man's release.

Mugabe capped over 3,000 graduating students.

Zimbabwe is facing rising joblessness due to a devastating economic downturn.