A man has been arrested after a French tourist was stabbed to death in what police say was an unprovoked attack in the Northern Territory outback.

Detective Superintendent Travis Wurst said a French man and his wife were at Connors Well rest stop, about 100km north of Alice Springs, on Wednesday afternoon when a man approached them, stabbing the 33-year-old French man in the neck "in an unprovoked attack".

The ABC was told the victim's 30-year-old wife flagged down a nurse and her husband in a passing car that was travelling from Alice Springs, to Ti Tree community, about 100km north of Connors Well.

The nurse reportedly stayed with the couple at the scene while her husband drove almost 40km north to the nearest telephone at the Aileron Roadhouse to call for police and an ambulance.

Connors Well roadside stop in the NT, where a French national was fatally stabbed. ( ABC News: Tom Maddocks )

He tailed the alleged attacker's car as he travelled along the highway to the roadhouse, the ABC understands.

BJ Gorman, the manager of the Aileron Roadhouse, told ABC local radio in Alice Springs that a man came in to call for help.

"We had a fella come in here to call the police, saying there was a stabbing at Connors Well," he said.

"[He said] some fella, some tourist got stabbed ... said another fella did stab him and took off."

Police were alerted and the alleged attacker's car was later spotted.

"Police saw that vehicle near Ti Tree; as soon as that vehicle had seen police it stopped and the person ran into the bush," Detective Superintendent Wurst said.

"Police were quite some distance away at the time, and because of that distance we weren't able to apprehend him at that time."

Police stayed in the area overnight and at first light on Thursday sent up a helicopter, and found and arrested the man nearby shortly afterwards at 8:30am.

Police are still establishing an exact timeline of events, and say that although they believe the French couple and their attacker were alone at the roadside stop, they are appealing for information from anyone in the area on Wednesday who may have seen a gunmetal grey Hyundai i20 hatchback with Victorian registration 1HU 1CC.

NT Police believe an offender who stabbed a man in the neck in Aileron was driving this vehicle. ( Supplied: NT Police )

The tourists were driving a 1998 maroon Toyota Rav4.

"We are extremely interested in speaking with anyone who may have sighted either vehicle, or had contact with any of the occupants of these cars in the days leading up to yesterdays incident," Detective Superintendent Wurst said.

Whether the 35-year-old arrested man is a local or from elsewhere is yet to be determined.

Wife treated for shock after 'absolutely devastating' attack

The victim's partner is being treated for shock at Alice Springs Hospital and has not yet been interviewed by police, Detective Superintendent Wurst said.

"One can only assume this is an absolutely devastating occurrence for her and for her family and that of the deceased as well, our thoughts go out to her and her family," he said.

"We'll investigate this matter thoroughly and efficiently and we'll bring this offender to justice."

Police are yet to charge the man they are holding in custody.

The French consul-general is aware of the incident, Detective Superintendent Wurst said, but it is not yet known what support is being provided to the victim's wife.

Police urge anyone with any information about the incident to contact police on 131 444 or Crime Stoppers on 1800 333 000.