Police are investigating a report of a sexual assault at St Nicholas Church yard in Brighton.
The offence, against a 28-year-old woman, is alleged to have occurred at the location, off Dyke Road, sometime before 3.30am in the early hours of this morning.
The area has been cordoned off while a forensics examination is carried out.
Residents tweeted that there was antisocial behaviour in the churchyard early yesterday evening, and one said the disturbances continued until 4am.
A 30-year-old man, of no fixed address, was arrested on suspicion of rape and remains in police custody at this stage.
Anyone with any information is asked to contact firstname.lastname@example.org or call 101, quoting serial 113 of 10/05.