The Papua New Guinea police commander for Manus Island said he deployed eight staff at the asylum seeker detention centre to maintain law and order.
David Yapu said the PNG immigration department asked him to provide a police presence after the Supreme Court in PNG ruled the centre was illegal.
A detainee has said police are now controlling the compound, but Mr Yapu said police are assisting the management.
"Their presence at the centre has calmed down the situation. So far I've been getting briefs from them on a daily basis that the situation at the center is quiet and normal."
David Yapu said police are stationed outside and not inside the detention centre.