Greens senator Sarah Hanson-Young has accused the government of being in "cover-up mode" after the first day of a Senate inquiry into the Nauru detention centre.
"The fact is this Government is in cover-up mode. They've been caught out ignoring the very real threat and dangers to children and women inside this camp," Hanson-Young said in Canberra on Wednesday.
"This [immigration] minister needs to take responsibility for the continued mental torture of children inside Nauru, the children he threatens every day to keep sending back there and for the women that have suffered at the hands of intimidation inside the camp."
The federal government has accused senators holding an inquiry into conditions at the Nauru detention centre of embarking on a witch hunt and deliberately delaying proceedings to only hear one point of view.
"Labor and the Greens today combined to ensure only one point of view was presented," immigration minister Peter Dutton said in a statement.
"The Department's evidence would clearly be an inconvenient truth for this Labor-Greens witch hunt," he said.
But the minister said the Department would still cooperate with the inquiry despite labelling it a "stunt" and a "waste of time and taxpayers' money."
The Senate inquiry was announced in March after the Moss Review revealed allegations of rape, sexual assault and intimidation at the detention centre. It found evidence of guards trading drugs for sexual favours.
The first public hearings into claims of abuse at the Nauru centre began Tuesday, but ran out of time to hear evidence from immigration department officials.
The inquiry heard from executives from Transfield Services, the company that runs the detention centre, representatives from the sub-contracted security firm Wilson Security and representatives from the charity Save The Children Australia.
Executives from Transfield Services, who have a $1.2bn contract to run the centre, weren't able to answer many of the questions put to them about allegations of abuse and sexual assault and conditions of the accommodation on the island.
Transfield senior executives took many of the questions on notice, claiming they did not have the details of basic information to hand. These questions included what the average temperature is on Nauru and how many female guards they employed.
Greens senator Sarah Hanson-Young asked about allegations of sexual exploitation, and Transfield logistics manager Derek Osborn could not say when he was first told about them.
The inquiry also heard from Save The Children, an organisation that provides support to detainees and runs a school at the Nauru detention centre.
Nine Save The Children staff were pulled from the island last year by the immigration department amid allegations they were coaching detainees to self-harm and telling them to fabricate abuse claims. The Moss Review found no evidence that staff had engaged in these activities.
The submission from the Asylum Seeker Resource Centre revealed filthy conditions at the camp. "The ceilings of the tents are filled with mould. At night, condensation causes the mould to drip onto the faces of people as they sleep on stretchers".
The ASRC submission also reported a story from a man who "woke up one night and found a mouse nibbling the fingers of his two year old son."
The former magistrate of Nauru, Peter Law, said he feared for the safety of people granted asylum in Nauru, and said the country's police failed to properly investigate and press charges in incidents of rape against children and women.
Another submission from Labor member Dr Harvey Stern accused the previous Labor government of breaching the ALP Constitution when it established the detention centre in 2013.
He says the ALP National Platform reads "Children, and where possible their families will not be detained in an immigration detention centre" and yet the number of children in detention centres rose from zero to nearly 2000 under Labor in government.
Many of the submissions say the Australian government did not adequately respond to the serious allegations in the Moss Review.
But Peter Dutton insists the immigration department has taken sufficient action, such as implementing all the recommendations, setting up an independent Child Protection Panel and sending four Australian Federal Police officers to Nauru in an advisory role.
The Senate committee will hand down its findings by the middle of June.