A request by the United Nations special rapporteur on torture, Juan Mendez, to visit alleged WikiLeaks whistleblower, United States soldier Bradley Manning, was denied in April.
At the time, Manning was being held in solitary confinement at Marine Corps Brig, Quantico in Virginia.
Speaking through his lawyer, Manning accused the guards at Quantico of treating him differently to other prisoners and reported he had been forced to strip naked by guards every night.
Mendez said US authorities had “not been receptive to a confidential meeting” with Manning.
Manning’s incarceration at Quantico was widely criticised. However, US President Barack Obama said he had been informed by the Pentagon that Manning’s treatment was “appropriate”.
During April, the US Defense Department moved Manning, 23, from Quantico to Fort Leavenworth in Kansas. It said Manning was no longer held in solitary confinement.
Manning has been held in pre-trial imprisonment for almost 12 months.
Organisations including Amnesty International and the US-based Psychologists for Social Responsibility have expressed serious concern regarding his confinement.