The Commonwealth group observing the Papua New Guinea election says reported attempts of candidates to bribe voters is a major concern.
Polling has been extended into this week after widespread delays.
The group says the elections have seen some progress and some setbacks in the country's efforts to strengthen its democracy
Its Chairperson, Vanuatu's Edward Natapei, says significant challenges remain to achieve the efficient management of elections.
"Concerns were raised with the group about the rise of money politics in the campaign, including reported attempts by candidates to bribe voters, on a scale far greater than ever before. The Group encourages the further strengthening and enforcement of laws relating to campaign financing."
Edward Natapei says the group observed an unfortunate level of disorganisation and inconsistency in aspects of election management.