Anonymous workers in the Australian-run immigration detention camps on Nauru have detailed what they call the "systematic violation" of the human rights of child asylum seekers.

The claim is made in a report by workers from Save The Children and submitted to Human Rights Commission Inquiry into Children in Detention.

The workers say they cannot reveal their identities, but feel a moral duty to speak out about the conditions on Nauru.

The submission describes numerous cases of abuse, including children being sexually abused, bullied and threatened by fellow detainees.

The report describes a child being sexually abused in the detention centre, while security guards looked on and failed to intervene.

In one case, a female detainee who complained about bullying was the target of a planned sexual assault by a group of men, and yet she and her relatives were knowingly kept in a tent near the men who had made the threats.

The tent leaked water, and was near electrical infrastructure, creating a life threatening situation.

The anonymous workers report that criminal background checks are not always completed on local Nauruan staff, thereby increasing the risk to children.

It is noted that criminal and other background checks in local employees are not mandated in the contract to run the detention centre.

"It is particularly concerning given there have been several employees accused of physical, verbal, and the sexual assault of children," the workers wrote.

Morrison's spokeswoman says allegations 'very serious'

A spokeswoman for Immigration Minister Scott Morrison says the subject matter raised in these anonymous allegations is "very serious".

"The department is working with Save the Children and the government of Nauru to determine the veracity of these anonymous claims and to what extent they are credible or relate to current practice," the spokeswoman said in a statement.

"The department has also asked Save the Children if any such concerns have been raised by any of their staff and to provide a response to the government on the allegations made."

The Government has stated for weeks that it is awaiting the outcomes of the Human Rights Commission inquiry and any supporting evidence in the final report.

"The [Save the Children] submission addresses matters that are outside the terms of reference of the AHRC inquiry," the statement added.

The report states "many children are living in knowingly unsafe circumstances," due to what the Save The Children workers describe as the "unyielding and harsh" stance of the DIPB (Department of Immigration and Border Protection).

Staff say they are actively discouraged from advocating the removal of children, "except in the most extreme cases of documented harm".

The anonymous workers say children in detention are exposed to traumatic situations every day, such as self harming events and violence, which serves as triggers to past traumatic events.

'Blocked toilets with faeces on the toilets'

The report further outlines a lack of access to food, a lack of supervision, and young children being separated from their families across the network of detention centres.

Basic sanitation and hygiene is also a major problem according to the report, with the workers describing the family camp (OP3) as "overflowing".

"There are outbreaks of lice, gastroenteritis and school sores that are difficult to contain due to the use of common showers, common eating areas and close living conditions," the workers wrote.

The report states there are only two toilets for the new classroom at the detention centre for 200 children and local staff members cannot be relied upon to show up to work consistently to perform the cleaning of the facilities.

"There have been multiple times that the OP3 has 'run out' of water, resulting in overflowing and blocked toilets with faeces on the toilets or on the floor of the toilet," the report said.

Greens Senator Sarah Hanson Young says the submission is explosive and that child detainees should be removed immediately from the Pacific Island nation.

"It outlines sexual, physical, verbal abuse and a significant lack of child protection inside the detention camp," she said.

"It is unbelievable to think the Government cannot act in the face this evidence."

Mr Morrison has agreed to give evidence to the inquiry into children in Australian immigration detention on a date yet to be set.

The inquiry is expected to report to the Government before the end of the year.