A 49-year-old man is in custody after a woman believed to be his partner was discovered unresponsive near the Todd River overnight, NT Police said.

Police said the man had reported the woman being unresponsive along the riverbed around 12:20am Monday.

Emergency services arrived at the scene but the woman was pronounced dead “a short time later”, police said.

“Officers attended a nearby location and arrested the man, who currently remains in custody,” a statement said.

“It is believed the woman is the 51-year-old partner of the man.”

Police have established a crime scene at the site.

“Detectives are urging anyone who has information to make contact on 131 444 or make an anonymous report to Crime Stoppers on 1800 333 000, and quote reference P25012728,” police said.

“If you or someone you know are experiencing difficulties due to domestic violence, support services are available, including, but not limited to, 1800RESPECT (1800737732) or Lifeline 131 114.”