Amnesty International says the absence of permanent court and prison services in North Malaita in Solomon Islands is alarming given rebel activity in the area.
The organisation says there are at least two rebel groups operating in the area, thwarting efforts to maintain law and order.
London-based Heinz Schurmann-Zeggel, the head of the Australia-South Pacific region at the international secretariat, says the community is being intimidated by individuals with high-powered weapons.
"One is a band of youngsters with little to do, access to home brew alcohol. They are hanging around marketplaces, driving around in their cars provoking the community, police and RAMSI. The problem is there are additional individuals, they have access reportedly to high powered rifles that are taken quite seriously by the community and will require a very strong and visible presence of RAMSI force."
Mr Schurmann-Zeggel says Malaita is the most populous island and should not have to bring justice officials in from Guadalcanal when cases need to be heard.