A Sri Lankan asylum seeker held in detention on Nauru was arrested on Sunday after climbing a tree and threatening to jump.
The man scaled a large tree -- appearing to be about 10 metres tall -- near the family camp on Sunday morning.
Ian Rintoul of the Refugee Action Coalition told The Huffington Post Australia the man threatened to jump from the tree to commit suicide, just days after receiving news his refugee application had been rejected by the Australian government.
He said the man's wife and five-year-old daughter were also held in the camp.
"He recently got a first rejection, that seems to be what precipitated it," Rintoul said.
"He was up the tree and was threatening to jump, but was talked down by his family and by guards who indicated he would get a review if he came down from the tree, that his case would be reviewed. He came down but was arrested."
Rintoul said it was unclear on what charge the man was arrested, after he voluntarily came back to ground after hours in the tree's highest branches.
The tree-climbing protest came just two days after another asylum seeker, an Iranian man, staged a nine-hour protest on top of a the crane on Friday.
That man brandished a sign reading "World: Kids in Nauru Need Help."
Reza climbs crane in Nauru protest
Reza's crane protest continues, he has maintained the protest for eight hours already. His banner reads "World: Kids in Nauru Need Help". Nauru is a prison island for children and all refugees, in detention or out.Posted by Refugee Action Coalition Sydney on Thursday, 26 November 2015
He was taken to hospital after surrendering but was later arrested by Nauruan police, with Rintoul saying he too was on similarly unclear charges.
"He taken from hospital and arrested yesterday. His sister tried to see him, but they wouldn't let her, they wouldn't tell us a charge," he said.
"We don't know. They kept mentioning Wednesday, maybe as a court date. It doesn't matter though -- you're talking about Nauru. It could be for unlawful protest. There are a raft of draconian laws that restrict protest in public places."
Rintoul said tensions about overcrowding and safety were bubbling over on Nauru, as an Iranian woman was arrested and held overnight in police custody on Wednesday after protesting.
"There's a lot of turmoil and ongoing protests. People were trying to put six single women in one room, a 'cabinet' they call it. There's been a series of protests, so [detention facility staff] called the cops," he said.
"There are concerns over security with rapes and sexual assaults. They haven't burst out in terms of open protests, but there are a handful of people."
Rintoul said the group had heard little about either of the two men arrested in recent days, but said conditions in jail were concerning.
"People are very worried by the police, there's no rule of law, no lawyers or rights on Nauru.
"The people involved in the protests disappear into the judicial system. Refugees get very worried about what happens, because some come from countries where police have carte blanche and they've arrived in a place that seems the same."
"Police do what they like, hold them as long as they like, beat them, women are sometimes strip searched, prisoners are held without food or water... we have no access, you can't send the lawyer down to see how they're going."
The Department of Immigration and Border Protection has been contacted for comment.