An Oxford university graduate has handed back his degree in protest against the university's decision to host a conference of Christians who support efforts to "cure" homosexuality.

Christian Concern is holding a five-day event at Exeter College this month, which has angered students and gay rights campaigners.

Stonewall, a gay rights group, has condemned the decision made by the college, saying "gay students and many Christians will be deeply offended" by the group's appearance.

But Oxford has refused to cancel the conference saying it was not "commercially viable" to do so at this stage.

The rector of Exeter College, Frances Cairncross, said she was "especially dismayed that we should come under attack".

And now Michael Amherst, who studied English at Exeter College, has told the prestigious university he has been left with "little choice" but to return his degree.

In a letter to Cairncross, he writes:

"Exeter College is no longer a place with which I wish to be associated. I feel your replies to me, other students and members of the press have been sorely lacking. At no stage have you or the college apologised for not having adequate checks in place, for allowing this to happen or for the offence caused to current and past members alike."

He added he welcomed the college's decision to review future bookings but said he feared to many "this will merely appear a ruse to wait for the passing of the media storm".

The 29-year-old told the rector she had displayed a "lack of understanding of the issue at heart as well as a total lack of contrition".

"The very fact it happened is most offensive."

Amherst, who is a full-time writer and also works with Just Detention International to research the problem of sexual assault in prisons, added he remained "extremely grateful" to his former tutors for his education at Oxford but said he hoped they would understand.

Frances Cairncross, rector of Exeter College, said in response to the letter:

“I am sorry to hear that one of our graduates is unhappy about the conference.

The College is reviewing its policy on future bookings to ensure that groups holding conferences are appropriate to the ethos of the College. A Working Group has been set up, including both students and Fellows, to draw up a set of guidelines for private bookings at Exeter College.

"I would like to stress that this College has always been committed to creating an environment where its members of all sexual orientations feel respected and secure from any hostility.”

CORRECTION: We previously stated the conference was "organised by the college's governing body". We have now removed this phrase.