The Post Courier reports Sinai as saying the general election under way now is not an exception.
Asked about allegations of vote buying and ballot rigging in some parts of the country by media he said while it is happening, he has not had any formal reports of it as yet.
He said the Electoral Commission has tried its best but that the problems are not solely a PNG Electoral Commission problem.
"That is what is happening out there, vote buying, and all of those things we have to have evidence, and it can happen anywhere, we don't know. I have not been reported any as yet.
"Well, we delivered the election process and we want the election to be done - but when there is a crime, it becomes a law and order issue, we have election laws, and election offences, so we need to now record all those election offences and start investigating, if they need to be arrested they will be arrested -that is election offences," Sinai said.
"PNG had its own share of responsibility in this kind of elections - back in 2002 we failed the elections, 2012 we had issues and in PNG that is normal, there's always problems in the country, last election 2017 they said it was the worse elections, this election they say it is the worst, in 2002 they also said it was.
"We have tried our best, it is all of us our approach, it is not PNG Electoral Commission alone, but it is the PNGEC responsibility to facilitate, being ownership is different."
Meanwhile, with two more weeks of polling to go, ballot boxes will soon be transported from remote areas to for vote-counting to begin.
RNZ Pacific's PNG correspondent Scott Waide said the movement of ballot papers was taking place at a sensitive time because of high levels of mistrust.
Mr Waide said transparency with ballot papers is crucial.
"You have to satisfy tribe clan and the scrutineer candidates, rival candidates incumbents put all of that together you have a potent mix of disagreements and counter-attacks and all that."
In the first election result declared, caretaker Prime Minister James Marape was re-elected as the MP for Tari-Pori in Hela Province.