The Human Rights Law Centre in Australia says it's appalling that the Australian company running the offshore processing centre on Nauru is profiting from abuse.
Canstruct has disclosed it made a profit of more than US$30 million from the centre in seven months.
Canstruct's sole contract is with the Australian government to provide garrison and welfare support on Nauru.
The Human Rights Law Centre's director of legal advocacy, Keren Adams, said the centre continues to be the site of horrific and ongoing violations, including illegal detention, sexual assault and child abuse.
She said the family-run company must accept that the indefinite warehousing of men, women and children is not an acceptable business.
Adams says Canstruct could profit $US110 million until its contract expires in April 2019.
Canstruct was awarded the detention centre contract last year after Spanish company Ferrovial said it did not want to renew its deal with the Australian government.