Protesters will gather outside immigration department offices in Brisbane at lunchtime following the death of an Iranian asylum seeker on Manus Island.
Papua New Guinean police are investigating the death of the Iranian national at the detention centre, following riots on Monday night.
About 80 asylum seekers were also hurt, with most suffering head injuries.
One asylum seeker with a suspected fractured skull has reportedly been transferred to Brisbane's Mater hospital for treatment.
The Refugee Action Collective is organising a snap protest on Wednesday outside the Department of Immigration offices on Adelaide Street, in central Brisbane, to demonstrate against offshore detention.
"We think the government is responsible for the death and injuries there," protest organiser Mark Gillespie said.
"The whole policy is creating so much trauma and mental illness.
"The detention centre should be closed and those people should be brought to Australia."
The circumstances of the incident remain unclear amid reports on the ground that locals had been involved in the fight and had been possibly armed with machetes.
Immigration Minister Scott Morrison could not confirm those reports but hosed down claims that PNG police fired shots directly at asylum seekers.
