Supporters of Bradley Manning protest his imprisonment near Quantico Marine Corps base, March 20, 2011. (Evelyn Hockstein/FOR THE WASHINGTON POST)

Investigator Juan Mendez has only been allowed to access Manning in the presence of a guard, where the soldier's comments could be used against him in court martial proceedings.

Mendez, who is Argentinian, issued a rare reprimand to the U.S. government for not allowing unmonitored access, saying he was acting on a complaint “that the regimen of this detainee amounts to cruel, inhumane or degrading treatment or torture.”

Concerns about the detention conditions of Manning have been steadily rising since his arrest last May. Manning’s conditions allegedly include solitary confinement and being forced to sleep naked.

The Pentagon denied this week he was kept in solitary confinement, and President Obama said Manning's confinement met “basic standards.”

Manning’s conditions have drawn the attention of Amnesty International, the American Civil Liberties Union, a Welsh member of the British Parliament (Manning is Welsh-born and a U.K. citizen), and now his mother.

Susan Manning has written to British Foreign Secretary William Hague asking for British consular officials to visit him in military prison and check on his physical and mental health. Manning visited her son in Quantico Marine base in Virginia in February and wrote this about her visit:

I was very distressed by seeing Bradley....I am worried that his condition is getting worse.... I do not believe that Bradley is in a position to be able to request this himself, so I am asking as his mother on his behalf.

In a legal letter from Manning to U.S. authorities, which was released by his lawyer a month ago, he described in his own words the conditions of his confinement:

I was stripped of all clothing with the exception of my underwear. My prescription eyeglasses were taken away from me and I was forced to sit in essential blindness.

Manning also wrote about being put on suicide watch:

I became upset. Out of frustration, I clenched my hair with my fingers and yelled: “Why are you doing this to me? Why am I being punished? I have done nothing wrong.”

He also describes the experience of being stripped naked at night:

The guard told me to stand at parade rest, with my hands behind my back and my legs spaced shoulder-width apart. I stood at parade rest for about three minutes. … The [brig supervisor] and the other guards walked past my cell. He looked at me, paused for a moment, then continued to the next cell. I was incredibly embarrassed at having all these people stare at me naked.

The Washington Post editorial board wrote an op-ed “Pfc. Bradley Manning doesn’t deserve humiliating treatment” in March.

Manning is currently voted #9 on the 2011 Time 100 most influential people in the world list, three places above WikiLeaks founder Julian Assange.

Manning is accused of leaking confidential data, including more than 250,000 diplomatic cables, to WikiLeaks. His charges include “aiding the enemy,” a capital crime.

Assange is fighting a decision to extradite him to Sweden over allegations of sexual assault.