The apparent vandalism of 40 gay and lesbian books at a Harvard University library was an accident, a dean has said.

Campus police began investigating a potential hate crime when the books were found doused in urine last month.

However, the university now says the incident was caused when a library worker accidentally knocked over a bottle of urine on a shelf.

It is not clear why a bottle of urine was in the library.

Staff had taken several weeks to report the incident.

College Dean Evelynn M Hammonds told the Harvard Crimson: “While we should not minimise the seriousness of this incident, HUPD [Harvard University Police Department] is no longer classifying this incident as a hate crime,”

“This nuance in the facts in the case also explains why library personnel did not immediately report the incident and treated it instead as a prank.”

Marco Chan, the co-chair of the Harvard College Queer Students and Allies, said: “On the one hand, I feel relieved by the news – but on the other hand, I’m still holding breath on questions that are still unresolved.

“Why was there a bottle of urine on the shelf? Why did it take two weeks for library or HUPD to figure out that this was just an accident? Did someone suddenly come forward?”

Library staff said the books would be replaced.