About 30 asylum seekers have stitched their lips together and 500 are on hunger strike as a protest at the Manus Island Detention Centre becomes increasingly volatile, a refugee advocate says.
One man required emergency medical treatment after he swallowed razor blades, Refugee Action Coalition spokesman Ian Rintoul told AAP.
The immigration department, which on Wednesday denied there was a hunger strike at Manus, on Thursday confirmed some detainees were refusing food and water and engaging in self-harm.
A spokesman for Immigration Minister Peter Dutton said asylum seekers involved in the protest are being offered medical care.
"A small number of transferees have engaged in self harm," the spokesman said on Thursday.
"They have been offered appropriate medical care.
"There are also a number of transferees who are refusing food and fluids, again they are being offered appropriate support."
The protest, which began on Tuesday, has now spread across four of the centre's compounds where people are refusing to return to their rooms, Mr Rintoul told AAP.
He said tensions are rising and people are feeling anxious and desperate.
Mr Rintoul said detainees deemed to be genuine refugees by authorities were fearful of being transferred to a new centre on the island at East Lorengau, where they feared attacks by locals.
"There is no immediate security in terms of physical safety on Manus Island, but there is no durable security for refugees on Papua New Guinea full-stop," Mr Rintoul said.
The immigration department spokesman said the Australian and Papua New Guinean governments remained committed to regional resettlement arrangements.
Greens immigration spokeswoman Senator Sarah Hanson-Young said Australia was a "better country than this".
"I have grave concerns for all those detained at the Manus Island camp," Senator Hanson-Young said.
"As the level of self-harm escalates it is clear that the refugees inside feel they have nothing more to live for."
