A lawyer is calling Minister of Justice Kris Faafoi callous for not respond to a letter asking for a man to be exempt from extradition because of health issues.
In 2011 the Chinese government called for South Korean citizen Kyung Yup Kim to be extradited on allegations of killing a woman in Shanghai.
He took legal action after being surrendered by the minister of justice 2016, claiming he would be tortured in China.
The Supreme Court ruled three weeks ago that he would be extradited, after receiving assurances from the Chinese government that he would not be tortured.
He would have visits from New Zealand diplomatic representatives at his detention site every 48 hours to confirm no torturous activity was occurring.
But Kim's lawyer Tony Ellis said this was unenforceable and an empty promise.
He said the government was turning a blind eye to widespread torture in detention centres and prisons in China.
Aside from the risk of torture, Dr Ellis has argued Kim's health issues should prevent him from being surrendered.
He has a brain tumour, liver and kidney disease, and severe mental illness, with a psychiatric assessment in December stating he was at risk of suicide.
His psychiatrist wrote that this risk would increase if Kim was extradited.
Dr Ellis outlined this in a letter to the minister in December, and said he was appalled by the lack of response, three weeks on from the ruling.
"We're now making allegations that [the minister is] causing psychological torture, degrading treatment, disproportionately severe treatment, and not treating Mr Kim with dignity or respect."
Ellis was preparing a complaint to the United Nations Human Rights Committee.
"I think they'll take it very seriously, as they always do when it's cases involving torture."
The US State Department's 2021 report on China called prison conditions there "generally harsh and often life threatening or degrading."
The minister of justice said he had received the lawyer's letter about Kim but had not responded and was awaiting advice on the issue.
"We've got a process to go through, and we'll get advice about both the complaint when it arrives, and also take the health into consideration again."