The partner of a former New Zealand soldier being held in an Australian prison without charge says he's locked in his cell for most of the day.

Watch the full Checkpoint With John Campbell interview with Teresa Mariner here:

Ko Haapu was a bodyguard for Prime Minister John Key in Afghanistan in 2010.

He has been detained in Perth since October and faces deportation because he is a member of a bikie gang, despite having no criminal record.

His partner Teresa Mariner told Checkpoint with John Campbell he was locked in his cell nearly all day.

"He gets let out for his meals and to have a shower and then he's locked back in his cell for the rest of the day," Ms Mariner said.

She said being locked up in the maximum security prison without charge was affecting his mental state.

"He's really, really angry," she said. "He's let down, he's upset, he's confused."

"We can't get any information as to why he's there, [or] how long he's going to be there from anybody."

Photo: SNPA

Ms Mariner said it was as if the guards were trying to break him, to justify his deportation.

"He has his bad days where he's really frustrated and I sort of try talk to him," she said. "They're just trying to push and they're trying to get the reaction they want."

She said it was hard to stay calm when surrounded by "murderers and rapists and all sorts of people".

"They can't be the nicest people to be around, especially when you're not a criminal," she said.

"He's in that prison, and he's being treated as a prisoner. But as far as we're concerned, he's an immigration detainee."

Ms Mariner said they had experienced a lot of problems with the prison system, including last minute cancelling of bookings, sexual remarks from a guard, and their daughter being denied entry to a child-friendly Christmas party.