Zimbabwe's anti-corruption commission says it is probing the circumstances surrounding the controversial awarding of a doctorate to former first lady Grace Mugabe.

Mugabe, whose husband resigned in November under pressure from the military and ruling party, received a doctorate from the University of Zimbabwe in 2014 amid allegations she did not study for it. Former president Robert Mugabe was chancellor of the university.

The southern African country's anti-corruption commissioner in charge of investigations, Goodson Nguni, says lecturers in the sociology department asked for the probe after failing to find any record of Grace Mugabe as a student.

Grace Mugabe's political profile had been on the rise in recent years, and fears that the unpopular first lady was positioning herself to succeed her 93-year-old husband led the military to step in.