Children Out of Immigration Detention, or ChilOut, says an Australian Bill which would allow force to be used in immigration detention provides no safeguards for children.
Amendments to the Migration Act would make immigration officers largely immune from liability for using force on detainees, if it is believed necessary to protect others in detention or maintain good order.
Australia also runs detention centres in Nauru and Papua New Guinea.
ChilOut's Claire Hammerton says under the UN Convention on the Rights of the Child, Australia is obliged to ensure children are given special protection.
Ms Hammerton says the Bill would allow force to be used in situations such as peaceful protests.
"Children may very well be present at the time of there being some kind of disruption, protest, and what this Bill does is effectively mandates the use of very severe force, that we would say is completely inappropriate in relation to children. And there are absolutely no safeguards in the Bill for protecting children in such circumstances."
Claire Hammerton says there are 124 children in immigration detention in Australia and dozens in the camp Canberra runs on Nauru.