Police are on high alert with refugees expected to stage major protests on Nauru.
There's growing tension on the island between locals and refugees now living in the community.
Refugee Action Coalition spokesman Ian Rintoul said a major protest was planned for Friday.
Mr Rintoul maintained the demonstration would be peaceful but refugees wanted to show their disgust at "being treated like slaves" by the Nauru and Australian governments.
The Nauru government is increasing the presence of police and private security guards at the power station, fuel depot, airport, hospital, government buildings, parliament, court house, harbour and ports, phosphate mines and other buildings.
In a notice distributed publicly, the government warned would-be trespassers that unauthorised access to designated areas would result in criminal charges and could attract fines of $200-$10,000 or one year in jail.
