Nauru police are reported to have arrested an Iranian asylum seeker who staged a nine-hour protest on top of a crane on Friday.
Reza Khestinzhad was taken to the IHMS clinic on Friday evening after he ended the protest and came down from the crane.
But on Sunday police arrested him at the clinic and took him to the police station, where he is being held.
According to the Refugee Action Coalition's spokesperson, police say he will be held until Wednesday but haven't made it clear whether he would be charged.
Ian Rintoul says he is worried about Mr Khestinzhad's welfare.
He says the police are following government moves to stifle any form of public protest in the country.
Mr Khestinzhad has been on Nauru for two and half years, with his wife and daughter.