Risque games at university orientation, such as asking freshmen to pretend to ejaculate into the face of a fellow student, are "reprehensible" and cannot be tolerated, said Acting Minister for Education (Higher Education and Skills) Ong Ye Kung.

In a Facebook post yesterday, Mr Ong said he has asked that university orientation activities be carried out in a manner that respects the dignity of freshmen.

His comments followed a recent report in The New Paper which highlighted complaints about increasingly sexualised activities at recent National University of Singapore (NUS) orientation camps.

The report also noted orientation activities made students re-enact rape scenes among other activities.

Mr Ong said orientation activities can be creative and even wild, but must respect human dignity.

"Activities can be rigorous, creative, even wild; students may push boundaries. But at all times, we must respect human dignity and remember the point and purpose of a university education," he wrote.

He described one of the activities freshmen had to go through - pretending to ejaculate into the face of a fellow student - as "reprehensible".

Mr Ong also pointed out that making the students act out rape scenes "not only degrades the real suffering of rape victims, it inflicts fresh humiliation on female students".

"Protesting (against) such acts has nothing to do with being prudish or a bad sport, (but) everything to do with respect for human dignity," he said.

NUS is conducting an investigation into the reported orientation activities and will take "strong disciplinary actions" against those responsible, he wrote.

NUS said on Tuesday that its staff, who used to run spot checks on the camps, will now be at the camps throughout. It said that as part of its practice each year, the Office of Student Affairs (OSA) had conducted sessions with students involved in organising orientation activities.

All proposed orientation activities also had to be cleared by the relevant supervisors, as well as OSA.