Footage of six boys being gassed at the Don Dale detention centre in 2014 has led to widespread condemnation of conditions for youth detainees.
All six are seeking damages for mistreatment, the Australian Broadcast Corp (ABC) reports.
But the NT government says the boys caused serious damage to the centre.
According to the ABC report, authorities say the damage, costing A$89,000 ($67,000;£51,000) ,was caused when the boys escaped from the centre in 2015.
