Northern Territory Police have arrested a man in relation to a sexual assault in Darwin City overnight.

Between 8.45pm and 9:30pm, it is alleged a woman was sexually assaulted by a man who was unknown to her, on The Esplanade.

The female victim was taken to Royal Darwin Hospital for assessment.

Police have since arrested a 35-year-old man who is expected to be charged with Sexual Intercourse Without Consent and Deprivation of Liberty.

Detectives from Sex Crimes Division continue to investigate the incident.

Police urge anyone who may have information relating to this incident to contact police on 131 444 and quote reference P24157106.

Anonymous reports can also be made through Crime Stoppers on 1800 333 000 or via https://crimestoppersnt.com.au/.