The Nobel prizewinner Derek Walcott has withdrawn from the race to become Professor of Poetry at the University of Oxford, claiming that the competition for the post has become “a degrading attempt at character assassination”.

Walcott’s withdrawal comes after an anonymous letter campaign against him. A formal ballot will be held on Saturday to decide who should take over from Christopher Ricks, the incumbent.

Documents containing details of a sexual harassment claim made against Walcott by a Harvard student in 1982 were sent to between 100 and 200 of the 150,000 Oxford academics and graduates who are eligible to take part in the vote.

Although the allegations have been made public before, the anonymous manner in which they were circulated suggested that the usually genteel competition had turned into an unscrupulous struggle. Yesterday Walcott, 79, decided to withdraw.

“I am disappointed that such low tactics have been used in this election and I do not want to get into a race for a post where it causes embarrassment to those who have chosen to support me for the role or to myself,” he said.

“I already have a great many work commitments and, while I was happy to be put forward for the post, if it has degenerated into a low and degrading attempt at character assassination, I do not want to be part of it,” he told the London Evening Standard.

A spokeswoman for the university expressed disappointment at Walcott’s decision. She emphasised that Professor of Poetry was not a teaching position. “Should Derek Walcott have won, he would not have had to give any tutorials. The [holder] only gives a series of public lectures, therefore any questions regarding harassment are not relevant and we cannot comment on them,” she said.

Walcott, who was born in St Lucia, has been described as the West Indies’ greatest writer. He won the Nobel Prize for Literature in 1992 and had been backed for the Oxford job by the author and Oxford don Hermione Lee, the novelist Alan Hollingshurst and the poet Jenny Joseph.

His withdrawal from the race increases the chance that a woman will take the post for the first time. This month Carol Ann Duffy became the first woman Poet Laureate.

The clear favourite now for the Oxford post is Ruth Padel, 63, a former chairman of the Poetry Society and the great-great-granddaughter of Charles Darwin. Padel is up against Arvind Krishna Mehrotra, 62, a literary critic and professor of English at the University of Allahabad, India.

About 150,000 members of the University of Oxford, including any graduate who has been through a graduation ceremony, and members of the University Congregation are entitled to vote. The result will be announced on Saturday evening. At the last election five years ago, when Ricks won, 500 votes were cast. The publicity surrounding Walcott’s nomination is likely to ensure a higher turnout this time.

The controversy has highlighted the murky area of staff-student relationships at universities. Such relationships are not uncommon, but the unequal balance of power between students and lecturers can leave students vulnerable to exploitation and unwelcome pressure. The University College Union (UCU) advises staff to “declare any relationship with a student, especially a sexual or romantic one, to an appropriate superior, colleague or third party designated by the university after consultation with UCU”. Many universities have no formal policies, however, and even where such policies do exist few relationships are ever declared.

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