An Air Niugini flight into Bougainville over the weekend was redirected soon after landing in Buka.
Francis Tokura, who is in charge of enforcing the Covid-19 State of Emergency in Papua New Guinea's autonomous region of Bougainville, ordered the measure on Saturday.
The flight was carrying 11 passengers, including the Bougainville's regional MP in the PNG parliament, Joe Lera.
Mr Tokura told NBC that flights carrying passengers will only be allowed when Bougainville has quarantine facilities available.
That facility is expected to be ready tomorrow.
Bougainville doesn't have any Covid-19 cases, although they are waiting on laboratory results from several people of interest.
President John Momis has said it's vital the virus is kept out of Bougainville because the region had no capacity to deal with an outbreak.
Mr Tokura said currently only cargo flights were being allowed into Bougainville.