The University of Oxford has launched an urgent investigation after a porter allegedly asked a black graduate if he used to "rob" the place.
The alumnus returned to St John's College on Tuesday to take a nostalgic tour of his former halls of residence,
But, after arriving, he claimed a porter made comments asking him if he used to "clean the windows" at the college or "rob it".
He wrote on Twitter: "Ey I went to my old college in Oxford yesterday to look round again. At the door I explained to the porter that I used to go there & he replied 'What did you do, clean the windows? Rob it?"
Shocked at the staff member's statements, he complained to the college - which was founded in 1555 - and an investigation was launched.
In a statement to the Evening Standard, a spokesman for the college said: "St John’s College is committed to ensuring the welfare and well-being of a diverse college community, and there is no place for discrimination of any kind.
"We are aware of a Twitter post about discriminatory language used by a member of staff towards a visitor, and are investigating this incident as a matter of urgency and will take action if appropriate."
The Tweet has been shared hundreds of times and attracted dozens of comments in support of the graduate.
Oxford students have voiced their concerns about the behaviour of porters at the university in the past. Last year, the students' union said porters should go on unconscious bias training after complaints about the disproportionate number black students being questioned about why they have entered college grounds.
Traditionally, each college employs a team of porters who control entry and provide security.
