Girls at Al-Taqwa College have been banned from running at sporting events because the principal believes it may cause them to lose their virginity, former teachers claim.

The schools regulator, the Victorian Registration and Qualifications Authority, is investigating the allegations, which have been referred to the state and federal education ministers.

It follows revelations in The Age last month that the principal of the Islamic school, Omar Hallak, told students that Islamic State was a plot by Western countries.

In a letter sent to the education ministers this week, a former teacher said female students were being discriminated against at the Truganina school.