Papua New Guinea Police Commissioner David Manning said people should not speculate on sensitive issues which are under police investigation, especially during the general election.
The commissioner issued the advice as he confirmed that five suspects are in police custody over the 1.56 million kina ($US440,000) in cash that was found in a suitcase in Hela Province just before the election started.
A polling station Lae, Morobe Province Photo: Raguel Kepas
He said the investigation is continuing into "this sensitive matter" and has pleaded for people not to speculate or spread rumours.
One of the men arrested is Mospal Marape, the son of the prime minister.
James Marape confirmed to media as he cast his vote on Monday that his son had been arrested but added that Mospal Marape had no association with the luggage.
Mr Manning said irresponsible comments or unsubstantiated rumours on social media can cause fear and possibly public disorder, while derailing police investigations.
He said police also know of some who are spreading fake news.
Significant police presence in the highlands
More than 200 police personnel from the National Capital District have been deployed for election duties outside of Port Moresby for the election.
They are working in several highlands provinces.
Assistant Commissioner Philip Mitna said the police are providing the security overlay for the Electoral Commission and he has urged everyone to stay focused on the mission and do what is right.