A probe into the so-called "sex for marks scandal" has been initiated, Higher Education and Training Minister Blade Nzimande said on Wednesday.

Speaking during his budget vote in the National Assembly, he said claims that university lecturers approached students for sex in exchange for better grades were worrying.

"I am extremely concerned about the allegations of sex for marks practices at our higher education institutions which mainly affect our female students, where male lecturers demand sex in order to pass some of the female students," said Nzimande.

Several universities, including the Walter Sisulu University, had cases of woman students reporting that lecturers offered them better marks if they engaged in sexual acts with them.

"That must be strongly condemned and in dealing with this I will be asking the oversight committee on transformation of South African universities to investigate these allegations and provide me with recommendations," said Nzimande.