Solitary confinement is among alleged human rights breaches against a former US military pilot held in a NSW prison as he awaits extradition proceedings.
A complaint to the NSW Ombudsman alleges Daniel Duggan, an Australian father and former US military pilot, was held in maximum security isolation for more than 230 days despite his lack of convictions or violence.
Prison operator Corrective Services NSW strongly denied the claim and said solitary confinement was illegal.
The 55-year-old former marine has not been charged with any Australian crime but faces extradition to the US on arms export law charges, which he denies.
Saffrine Duggan's letter to the NSW Ombudsman states her husband's detention "can only be considered a clear and outrageous breach" of United Nations human rights obligations that include a 15-day limit on solitary segregation.
"Dan's 230-day stint in solitary confinement torpedoes the UN limit of 15 days," the letter said.
"His incarceration breaches UN treaties that the Australian government has signed - effectively having Canberra and its partners in the NSW government who operate prisons in the state - in breach of their own commitments."
Under the Mandela Rules, the UN defines solitary confinement as the isolation of prisoners for 22 hours or more a day without meaningful human contact.
Duggan was held in the maximum-security Silverwater remand centre from his arrest until March, when he was moved to the maximum-security Lithgow Correctional Centre.
Until mid-December, he was held on an "extreme high risk" security classification.
Duggan, who met NSW Ombudsman for Detention and Custody Kate Smithers on June 1, was released to an exercise yard on Friday and Saturday.
That was the first time he'd been granted such access since his arrest, his family says.
"While it is a tiny relief that Dan was finally allowed out of his cell into a caged area in the fresh air for a short time this week after a lot of external pressure, that does not let them off the hook for his treatment over the past seven and a half months," Mrs Duggan said in a statement to AAP.
Corrective Services NSW vehemently denies the claim, saying it obeyed NSW law dictating inmates must be allowed two hours of open-air exercise per day.
The only exceptions are poorly-behaved inmates, whose entitlement is halved to one hour, or when operational or administrative issues arise, such as understaffing.
"The safety and wellbeing of people in custody is Corrective Services NSW's top priority," a spokesman told AAP.
Duggan, a former US Marines naval aviator and flight instructor, is accused of conspiring to provide military training to the People's Republic of China relating to aircraft carrier approach and landing.
He allegedly provided military training to Chinese pilots in 2012 and conspired to launder payments for the services.
Duggan has consistently denied the charges, filed in a US court in 2022.
His case returns to court on July 25 when eminent barrister Bret Walker SC will argue for a temporary stay in proceedings.
That would be to allow an intelligence agency oversight body to finish its inquiry into Duggan's case, including his return to Australia from China before his arrest.