The United Nations has suspended its tour of Australian detention facilities and accused the country of a "clear breach" of its obligations under the Optional Protocol to the Convention Against Torture (Opcat).
The New South Wales government has refused inspectors entry into any facilities in the state and Queensland has blocked access to mental health wards.
In a statement released on Sunday evening, the subcommittee on the prevention of torture (SPT) announced it had stopped the visit following repeated access and information gathering issues.
"The SPT delegation has been prevented from visiting several places where people are detained, experienced difficulties in carrying out a full visit at other locations, and was not given all the relevant information and documentation it had requested," the statement read.
"Despite its continued efforts to engage the authorities for the resolution of the problems, the SPT continued to be obstructed in the exercise of its mandate.
"As a result of this, the SPT members felt that their 12-day visit, which began on 16 October and was due to run until 27 October, had been compromised to such an extent that they had no other option but to suspend it."
The statement claimed that there had been a "clear breach by Australia" and noted there was a misunderstanding about what the visit was for.
"State parties have an obligation to both receive the SPT in their territory and allow it to exercise its mandate in full," delegation head, Aisha Shujune Muhammad, said.
"It is deeply regrettable that the limited understanding of the SPT's mandate and the lack of cooperation stemming from internal disagreements, especially with respect to the states of Queensland and New South Wales, has compelled us to take this drastic measure.
"This is not a decision that the SPT has taken lightly."
Muhammad said it was "concerning that four years after it ratified" it appeared Australia has "done little to ensure consistent implementation of Opcat obligations".
Last Tuesday, inspectors had been refused entry to a Queanbeyan facility.
"The whole role of our jail system is to keep people safe, protect us from the criminals that we lock up every day," NSW corrections minister, Geoff Lee, said.
"It's not to allow people just to wander through at their leisure. [The UN] should be off to Iran looking for human rights violations there."
Guardian Australia revealed that Queensland would allow inspectors into the state's prisons but not to access inpatient units where people ordered to undergo treatment or charged with crimes were being held under state law.
Opcat was ratified by the federal government under the former prime minister Malcolm Turnbull in 2017. This is the first time inspectors have visited Australia.
Under its mandate, the SPT is able to make unannounced visits to all detention facilities and conduct private interviews with people deprived of their liberty without witnesses.
The former prime minister Malcolm Turnbull warned the New South Wales and Queensland governments to "think carefully about the international company they are keeping".
"If a jurisdiction does not allow UN inspectors to visit facilities in accordance with the protocol, for whatever reason - the obvious question will be, what do you have to hide?" he said.
