Sir Michael made the call after major Australian media ran the report of Namah who was an opposition MP at the time of the alleged offence.
He allegedly sexually harassed a male blackjack dealer at Sydney’s Star Casino last year before being thrown out for threatening staff.
“As leaders we are the face of Papua New Guinea when we visit an overseas country. Our conduct must reflect our respect for the position that we hold and the people that we represent,” Sir Michael said.
“I know many Papua New Guineans are embarrassed that an elected representative, therefore a leader of government, can behave in such a shameful and disorderly manner.”
He said O’Neill should not remain silent about the conduct of his deputy anymore.
“Too many allegations are already stacking up against Namah.
“The alleged amount of money held by the casino, of A$800,000, for Namah is also alarming.
“I would suggest that before any investigation is even set up that O’Neill stop his deputy from further representing PNG overseas at the expense of the PNG government.
“This is an election year and Namah is also calling for the deferral of election. If given more time, Namah will destroy himself.
“All that aside, the election must go ahead as scheduled.
“There are many disciplined, innovative Papua New Guineans out there who can better represent our aspirations on the floor of parliament, in public and abroad.
“I call on the people of Vanimo-Green to elect a leader who will bring services to your electorate
and whose conduct will also be beyond question at all times.
“Finally, I call on O’Neill to keep his word and do whatever he can within his power not to allow the election to be deferred by Namah or other members of parliament,” Sir Michael said