Manus Acting Police Provincial Commander, Senior Inspector David Yapu, revealed this when raising his concerns over the increasing trend.
He is now appealing to the community leaders in the province to speak up about this immoral practise within the family unit following recent reported incidents of young girls being sexually assaulted by male members of their own families.
He is calling on families to work together with police to address these issues.
PPC Yapu raised concerns after police arrested a 54-year-old father on Feb 28 over allegations he sexually assaulted his 14-year-old daughter at their family home on Feb 25.
The father, whose identity is withheld due to the age of the victim, was charged with three counts of sexual penetration, persistent sexual abuse and incest.
The man, who is from the Lelemadih-Bupi Chupei Rural LLG, is currently held at the Lorengau police station cells and will appear for mention at the Lorengau District Court today (March 8).
In a similar incident, a 12-year-old girl was also sexually violated by her big brother in their family home on February 5 at one of the villages in the Pomutu-Kurti-Andra LLG. She has received medical treatment at the Lorengau General Hospital.
The offense was reported to police on Monday, March 6.
The victim suffered severe bleeding after she was allegedly violated by her brother and was transported by boat to Lorengau for treatment.
The suspect, whose identity is known to police, is still on the run and PPC Yapu said his men will soon arrest him.