A New Zealander in a west Australian detention centre says detainees involved in a hunger strike just want to have their freedom.
Lee Barber, who is originally from Stratford in the Taranaki but has lived for 45 years in Australia, said he had only been drinking water but did not know how long he could last.
"There's been no medical come around," he said.
"A couple of the staff have asked how we're going ... but I think that's just general conversation more than anything."
Mr Barber said he had no family in New Zealand but the threat of deportation was always real.
Detainees say more than 350 of them have been refusing food since last Monday at Yongah Hill Detention Centre in Perth.
They are striking because they say their living conditions are inhumane.
Last week, some detainees at a Melbourne Immigration centre refused to attend regular meals as part of a protest.
Earlier, Advocate Ian Rintoul from the Refugee Action Coalition said there's a large population of New Zealanders in Yongah Hill and there could be 50 people on strike.
But Australia's Department of Home Affairs said there had not been a mass hunger strike in either the Melbourne centre or Yongah Hill.
Mr Rintoul said detention centre conditions were poor.
"Chairs are bolted to the ground, they're all stainless steel. They're [detainees] locked in their rooms from midnight to 7am.
"On top of that there are questions of long-term detention. People have got complex cases, there are visa cancellations, there's no legal support. It's very difficult for them to understand what's going on."
He said there were up to 10 New Zealanders in the Melbourne centre, and dozens in Yongah Hill.
"In Yongah Hill there's a large population of Kiwis.
"Now it's difficult for me to say how many are actually involved in the hunger strike in Yongah Hill but my best guess would be in the vicinity of 50 or 60 actually. It could be more."
He said people were striking to draw attention to the conditions inside the detention centres.
Border Force says detainees are treated well
In a statement, a spokesperson from Border Force said: "There is no mass hunger strike at Yongah Hill IDC or MITA (Melbourne Immigration Transit Accommodation). While some detainees are refusing to attend regular meal times as part of a protest, they continue to eat and drink in other parts of the facility."
Mr Rintoul said in Melbourne, a high-security centre closed and detainees were transferred to another centre, MITA.
Last week, in response to the protest in the Melbourne centre, the Border Force denied conditions in its centres were inhumane or brutal.
"Detainees in immigration detention are given access to good food, medical care, educational programmes, cultural, recreational and sporting activities, internet and computer facilities, televisions, and clean, comfortable sleeping quarters that include mattresses.
"The detention population has changed considerably in recent years with a significant number of the population having their visa cancelled on character grounds, based on criminal convictions and links to criminal associations such as outlaw motorcycle gangs or organised crime.
"On this basis, detention facilities and amenities are designed to be comfortable, while also ensuring the safety and security of detainees, staff and the public."