Some male lecturers in Ghana and Tanzania "consider it their right to demand sex for grades", researchers at the University of Sussex have found.
Louise Morley and Kattie Lussier wrote their study after encountering widespread reports of sexual harassment suffered by female students during separate research on widening participation in the two countries' higher education systems.
In a paper, Sex, Grades and Power: Gender Violence in African Higher Education, they say the "hierarchical power relations within universities appear to have naturalised a sexual contract in which some male academics consider it their right to demand sex for grades".
This has led to the "construction of negative female learner identities", they add. "If women fail, this is seen as evidence of their lack of academic abilities and preparedness for higher education. If they achieve academically, this is attributed to prostitution."
Professor Morley, director of the Centre for Higher Education and Equity Research at Sussex and lead researcher, said sexual harassment in universities is not limited to Africa.
"It's a global issue," she told Times Higher Education. "It's about power and the abuse of power."
The paper, presented at a Society for Research into Higher Education conference last month, cites interviews with staff and students.
Professor Morley and Dr Lussier conducted 200 interviews with academics and policymakers and 200 life-history interviews with students.
The paper quotes an academic manager from a Ghanaian university, who said: "Sexual harassment is a way of life at this university ... the female students are very vulnerable to lecturers ... and the girls think that's a legitimate way to get marks. Boys think the girls have an advantage" as a result.
A female Tanzanian student cited in the paper said that "being a girl costs sometimes. There are corrupt staff. If you want help, they say you have to do this or that ... it is not your fault but he does that so that he can get you ... get sex."
A male Ghanaian student cast doubt on the achievements of female students.
"Sometimes you will see a woman in a class or maybe in a group discussion ... you wonder how she got admission. But when the paper comes she performs better than you ... Sometimes some women have been favoured."
Professor Morley, who hopes to research the issue further, said the interviews showed that sexual harassment had become "normalised" within some universities.
Male students' assumptions about "prostitution" among their female peers "diminished women's achievements", she said.