Hundreds of Egyptian students are marching in front of the Education Ministry in Cairo over the cancellation of some high school exams.

Monday's march comes after 12 Education Ministry officials were detained after answers to the final nationwide exams for Arabic, religion and other subjects were posted earlier this month on Facebook by an anonymous user who said he wants to shine a spotlight on corruption and inefficiency.

Protests of such size are rare in Egypt, where President Abdel-Fattah el-Sissi has led a harsh crackdown on critics from among both the Islamist and the secular camp.

Egypt's education system has long been plagued by overcrowded classrooms and poorly trained teachers, forcing millions of students who can afford it to rely on private tutors. Exam scores directly determine entrance to universities.