The Abbott government knew about and tolerated the sexual and physical abuse of women and children asylum seekers on Nauru for more than a year, detention centre workers allege.
In an open letter published on the internet, 24 former and current teachers, doctors and charity workers say the immigration department was informed of assaults at the detention centre up to 17 months ago.
That was well before the government commissioned a review of the centre which uncovered dozens of cases of abuse.
The workers say the immigration department chose to ignore allegations of sexual assault against a boy in November 2013, leaving him in detention and exposing him to further abuse by centre employees.
They claim department management participated in weekly and daily meetings where several alleged assaults were discussed and were informed of specific cases in writing.
However, all children remained in the centre.
"Despite incident reports... the department failed to act to protect these children from harm," the letter says.
"It is important to highlight that many survivors who did come forward previously, still remain in Nauru subject to further abuse."
The cohort of workers, which includes former Nauru workers child psychiatrist Dr Michael Gordon and psychiatrist Dr Rodney Juratowitch, are calling for the transfer of all asylum seekers on Nauru to Australia.
The majority signed the letter anonymously, only listing their positions and which organisations they worked for.
They also want a royal commission into allegations of abuse on Nauru and the government's response.
"We are the only ones with first-hand knowledge of the detention centre environment who can speak the truth on behalf of asylum seekers and refugees," the letter says.
Immigration Minister Peter Dutton said the department had accepted all 19 recommendations of the independent Moss Review, which called for better processes to handle abuse claims.
"If people have further information to provide they should provide that to the department or to me so that matters can be properly looked at," Mr Dutton told Sky News.
The review also investigated claims Save the Children staff had encouraged asylum seekers to self harm and make false claims, but found no conclusive evidence.
