Police say they have been unable to confirm a reported sighting of a 14-year-old girl who has gone missing while hitchhiking to the Northern Territory.

Police say Mariah Angus was last seen on Wednesday, at a truck stop 40 kilometres north of Adelaide.

Police say they have received a report that the girl was seen in Tennant Creek, about 700 kilometres south of her hometown of Katherine, at two o'clock this morning.

She is described as being of Aboriginal appearance, thin and approximately 160 centimetres tall, with long dark hair.

Northern Territory police have the public to be on the lookout for the girl, who was last seen trying to hitchhike from South Australia to the Top End.

Police say Mariah Angus was asking for rides at a truck stop at Two Wells, about 40km north of Adelaide, on Wednesday.

Sergeant Ian Kennon says she was trying to reach Katherine.

"We have limited information at the moment, just what we've been supplied from the South Australian police," he said.

"What we understand is that the young girl, who is originally from the Northern Territory, was down visiting family.

"She has taken it upon herself to try to come back to Katherine and she's chosen to hitchhike to attempt to do that."

Sergeant Kennon says, despite the report of a possible sighting, fears are still held for the girl.

"Certainly hitchhiking is a concern for a young person. I wouldn't advise anyone to travel by those means," he said.

Anyone who may have seen Mariah, or who may know of her whereabouts, is urged to contact police on 131 444.