Immigration Minister Chris Evans said security would be increased to prevent a repeat of Saturday's mass brawl between Afghan and Sri Lankan detainees in the remote Christmas Island centre, far off Australia's northwest.
Australian Federal Police were investigating the matter, in which three inmates were seriously hurt and flown to Perth for treatment, and would charge those responsible if they could identify them, he said.
"Clearly though, security at the centre will be tightened to ensure we don't have any incidents like this again," Evans told parliament on Monday.
The violence followed the arrival of scores more asylum-seekers on rickety people-smuggling boats in recent weeks, and the repatriation of some Sri Lankans after they were found not to be refugees.
Evans said some Sri Lankans had become concerned they would also be sent home and tensions could have arisen because most Afghans held at the centre are ultimately given refugee status and resettled in Australia.
"That may well