Three asylum-seekers have begun a rooftop protest at the Villawood Detention Centre in Sydney's west.
There are also claims of confrontations involving police at the centre's perimeter fence and that fires have been lit.
The protesters on the roof are all male and have been held at the facility for about a year.
Earlier on Wednesday Immigration Minister Chris Bowen denied that Villawood detainees were on a hunger strike after the suicide of a fellow inmate.
Iraqi man Ahmad al-Akabi, 41, was found dead in his quarters at the detention centre on Monday night.
His was the second suicide of a detainee at Villawood since September