NT Police Force are investigating an alleged sexual assault on a female over the age of 18 in Ludmilla overnight.

About 12:15am, police received reports of a female that was allegedly sexually assaulted by a 32-year-old male known to her.

Police responded but were unable to locate the alleged offender and he remains outstanding.

St John Ambulance attended and conveyed the female to Royal Darwin Hospital for medical assessment.

Sex Crimes Detectives have carriage and investigations remain ongoing.