The hunger strikers at the Melbourne Immigration Transit Accommodation are demanding improved conditions.
They have not eaten since Tuesday, Iraqi detainee Ali Yousuf said, adding that the protest aims to achieve their demands, which range from the provision of "proper chairs and tables to do paperwork" to the freedom to venture outdoors after midnight without a guard, Presstv Reeported.
"I (have) never seen any detention center like this before," added the 30-year-old man, who fled Iraq after it was revealed that he worked for disgraced US military contractor Blackwater as an interpreter.
The Australian government and the private contractor SERCO, which staffs the facility, have not commented on the report yet.
The detainees expect to meet government officials on Thursday to try to find a solution to the issue.
Inmates at Australia's onshore detention centers, which house people who have infringed immigration law, often go on hunger strikes to draw attention to their plight.
In 2018, hundreds of detainees at a center in Sydney held a hunger strike against strict visitation rules.
The government denies mistreatment, but has vowed to "ramp-down" the country's "onshore immigration detention network."
Earlier this year, Australia announced the closure of the much-criticized Maribyrnong detention center.
But detainees say the new MITA facility, which locks up 223 inmates according to the latest official statistics, is worse.
In 2017, the Australian Human Rights Commission reported the excessive use of restraints and limited space and privacy at the center.
Refugee Action Coalition activist Ian Rintoul also urged the closure of the detention centers.