Benjamin Sullivan, 21, has been arrested on suspicion of one count of rape and and one of attempted rape, according to Guido Fawkes and The Tab.
Earlier this month, there were reports that he had admitted to being a member of the "Banter Squadron", an “elite” drinking society.
The Tab claimed he had also asked the Union to hand over more than £1,000 so that he could threaten legal action against the student newspaper, which revealed his membership.
It also claimed he:
"- LIED, claiming he'd never heard of The Banter Squadron
- Tried to BARGAIN with us, offering stories of other students taking drugs
- THREATENED The Tab with an injunction to stop us reporting the story"
He subsequently convened a meeting with the Oxford Union's senior treasurer and arranged for the society to pay him £1,000 plus VAT to meet the legal costs of gagging the paper. The agreement was apparently withdrawn after a revolt by 30 members who tried to have the matter debated in public.
The Union's librarian, walking out of a debate with Sullivan, would claim: "I joined this society because I believe in free speech and proper debate. Following a persistent campaign against me for ever questioning [Sullivan], I have suffered personal attacks."
The Daily Mail journalist Liz Jones was at the debate and claimed in her column that Sullivan was distracted.
Concern about the issue of sexual assault at the university is growing.
A Tumblr account set up last year in which students anonymously report sexual assault at the university has received dozens of submissions.
Earlier this year another student newspaper, The Cherwell, highlighted the fact that despite falling crime rates in the Thames Valley area, cases of dropped sexual assault charges remain high.