Less than half of the UK's top universities are reportedly taking note of incidents of alleged sexual assault against students.

Out of the total 24 Russell Group universities, seven said they did not consistently record sexual assault cases reported by students while seven reportedly recorded only some cases.

"You have to start with knowing how big the problem is. If you are not recording it, how do you know? If you do not have trained staff and clear reporting routes, how do you know?" said Dianne Whitfield, chief policy officer at Coventry Rape and Sexual Abuse Centre (Crasac).

An estimated one in five Russell Group universities were found to lack specific guidelines on how students can report instances of sexual violence, in confidence or as a formal complaint.

Amongst the universities, included Leeds, Liverpool, Cardiff and Manchester universities, as well as King's College London.

According to the National Union of Students, 60% of university students also had no knowledge of any university policies that addressed such issues.

"When 60% of students say they are not aware of any university codes of conduct that prohibit or tackle sexual comments, advances, intimidation or harassment it is clear that universities must face up to this issue," said Susuana Antubam, the NUS women's officer, reported The Guardian.

Few of the top universities that did record cases of sexual assault consistently noted double digit figures in high numbers.

According to several rape crisis groups, even these high numbers were a "gross underestimate" of the actual cases of sexual violence on campuses across the UK.

NUS president, Toni Pearce, is urging British universities to stop "passing the buck" and acknowledge the problem that seems to be growing on campuses.

"Harassment is rife on campus, but we still keep hearing from universities that there is no fear, no intimidation, no problem," said Pearce, reported The Guardian.

"Sadly, all of these elements exist in campus life, we know because we hear it from students. Today I say to universities everywhere the pass the buck approach of 'not on my campus' is now completely unacceptable. They must acknowledge the problems and join us in confronting them."

According to a NUS survey of 2,156 male and female students, an estimated 37% of women and 12% of men said they had experienced some form of sexual advance.