A man who flew from Victoria to Queensland then to the Northern Territory has tested positive for COVID-19.
The 65-year-old returned a "low positive" diagnosis for the virus on Monday but is not considered infectious, NT Health says.
"This gentleman had previously had COVID-19 in Victoria (and) had been cleared of (the virus) with a negative test result," NT Health Minister Natasha Fyles told reporters.
"An unusual test result."
He arrived in Darwin via Brisbane aboard Jetstar JQ674 on Saturday and was in quarantine at Howard Springs quarantine facility when he tested positive.
Ms Fyles said there was a "very low risk" other people in Howard Springs could become infected from the man, who was not showing any symptoms.
She said the man was also wearing PPE during his journey from the airport to the quarantine centre.
The man was moved to Royal Darwin Hospital and placed in isolation once a small amount of the remaining inactive virus was detected.
He will continue to be tested in the coming days.
NT's Acting Chief Health Officer Charles Pain said the case was not an "unknown phenomenon" and is a "weak positive" after a "number of cycles of replication".
"We've seen this around the country," he said.
"Fragments of the virus persist and we can detect them."
The man previously returned a negative test result on September 13.
NT Health said small amounts of the virus can remain after recovery and the diagnosis was not considered to be a new COVID-19 case.
The Northern Territory's virus case numbers remain at 34.