Hundreds of refugee supporters have gathered outside Sydney's Villawood Detention Centre to support three detainees protesting on the rooftop.
However, the centre's other detainees are in lockdown, unable to communicate with the crowd.
The supporters on Monday marched the two kilometres from Chester Hill Railway Station, in Sydney's southwest, to the detention centre to show their solidarity with those on the other side of the fence.
"Freedom," they chanted, and the cry was returned by the men on the roof.
The three men are in the sixth day of a protest that began on Wednesday, when a riot involving 100 detainees left nine buildings gutted by fire.
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Twenty-two of the alleged rioters were taken to Sydney's Silverwater jail.
Majid Parhizkar, 24, from Iran, and stateless Kurdish men Mehdi and Amir, whose applications for asylum have been twice rejected, are refusing to come down from the roof.
Majid's brother Hadi, 25, has been camping outside the detention centre since Thursday and says he is worried about his brother, who has been without food since the protest began.
"It's not good, he's very hungry and they can't resolve the problem," Hadi told reporters at the scene.
"It's dangerous for him and I want (him to come down).
"We came to Australia together two years ago and I was accepted after six months and Majid has not been and we want to know the reason."
His brother could not go back to Iran because he might be killed for converting to Christianity, Hadi said.
Majid felt as if he had nothing to lose and if he came down from the rooftop he might be sent to jail or be deported, he said.
The refugee supporters maintained a one-minute silence for Anzac Day, as police and detention centre security guards closely monitored the area.
