The Pontville centre near Hobart has been re-branded as an alternative place of detention by the Immigration Department and is being used to detain almost 300 unaccompanied minors from places like Afghanistan, Vietnam, Iran and Sri Lanka.
Authorities say the 11-year-old child is being held along with two cousins but the immigration department won't say how long the children have been detained.
Felicity Ogilvie reports.
Presenter: Felicity Ogilvie
Speakers: Professor Louise Newman, psychiatrist and asylum seeker advocate; Aloysius Mowe, director of the Jesuit Refugee Service; David Bycroft, executive chairman of the the Australian Homestay Network
FELICITY OGILVIE: The youngest detainee at the centre is an 11-year-old boy from Sri Lanka.
Psychiatrist and asylum seeker advocate, Professor Louise Newman, is calling for the boy to be moved.
LOUISE NEWMAN: And I think most people would not want to see children who are young in an environment here they're likely to be feeling frightened. They certainly are at risk: they're not in a position, often, to understand the situation that they're in and it would be much more appropriate for those children to be placed in foster families.
FELICITY OGILVIE: The 11-year-old child is being held together with his two older cousins who are also seeking asylum.
The Department of Immigration says it's focused on keeping the extended family together, but can't say when the Sri Lankan children will be moved out of the centre.
Professor Newman says children can suffer considerable mental stress while in detention.
LOUISE NEWMAN: We start to see children showing quite clear signs of trauma. Some children becoming very child-like, if you like - regressing to an earlier developmental stage - others starting to feel angry and frustrated.
FELICITY OGILVIE: There are almost 800 unaccompanied minors seeking asylum in Australia; 335 of those children are having their claims assessed in the community. Most are living in group homes, not foster care.
A Catholic organisation has been looking after unaccompanied minors in a Sydney house since 2010.
Aloysius Mowe is the director of the Jesuit Refugee Service and he says up to eight children live in a home where they attend school and play sport.
ALOYSIUS MOWE: The children do not get their childhood taken away from them. They basically live very ordinary lives as students, and we have found that this really contributes to their mental health.
And in the long term, it's a good outcome not just for the children; it's a good outcome for Australia, because a large number of these children are eventually found to be genuine refugees.
FELICITY OGILVIE: In a separate program, families are taking in adult asylum seekers into their homes.
And David Bycroft from the Australian Homestay Network wants to extend the program to include children.
DAVID BYCROFT: We think there's an opportunity for them to be hosted for the long term by going through a process to choose the right family that's interested in helping them and building the support structure around them that creates a relationship that can make that successful.