Papua New Guinea's caretaker prime minister James Marape has been re-elected as the MP for Tari-Pori in the country's Hela Province.

Mr Marape, is the first MP to be declared in what has been a chaotic polling period so far with at least two more weeks of polling still to come for other constituencies.

RNZ Pacific's PNG correspondent Scott Waide said, while Marape and his supporters will be celebrating the win, polling in the district has been steeped in controversy.

"Tari Pori was a fairly controversial area to be this week, you had incidences where money was smuggled in on a Air Niugini charter flight and it got intercepted by police and the allegations surrounding all of that linked to associates of the prime minister including his son," he said.

Marape last week told media that his son had no association with the luggage and that there was nothing illegal about it anyway.

He said, "the person who was transporting the money is the director of a construction company in Hela Province. Knowing there are checks at the airport, he brought the money, for him he felt the money was legal. He was transporting money for his company. He was being picked up and Police felt the money was suspicious on the eve of an election."

Waide said there were also reports of children being allowed to cast ballots and other election irregularities in the Tari-Pori district.