WASHINGTON – The Army private suspected of illegally passing US government secrets to the WikiLeaks website was transferred Wednesday to an Army prison in Kansas from the Marine brig in Virginia where he has spent the past nine months.

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Pfc. Bradley Manning, suspected of having obtained the classified documents while serving as an Army intelligence analyst in Iraq, is awaiting a determination by the Army on whether he is mentally competent to stand trial.

An Army spokesman at the Pentagon, Col. Tom Collins, said Manning arrived safely at the Joint Regional Correctional Facility at Fort Leavenworth, Kan., on Wednesday afternoon. Over the coming five to seven days he will undergo an in-depth physical and behavioral assessment by Leavenworth staff, Collins said.

Shortly after the Pentagon announced its decision to transfer Manning, the soldier's lawyer, David Coombs, wrote on his blog that his client's treatment at Quantico was substandard.

File photo of Pfc. Bradley Manning [Photo/Agencies]

"While the defense hopes that the move to Fort Leavenworth will result in the improvement of Pfc. Manning's conditions of confinement, it nonetheless intends to pursue redress at the appropriate time for the flagrant violations of his constitutional rights by the Quantico confinement facility," Coombs wrote.

The Pentagon said Manning would be returned to the Washington, D.C., area as needed for legal proceedings, since his case is under the jurisdiction of the Army's Military District of Washington. No trial date has been set.

Jeh Johnson, the Pentagon's top lawyer, said the transfer to Fort Leavenworth does not suggest that Manning's treatment at the Marine base at Quantico, Va., was inappropriate. But he acknowledged that the case received high-level Pentagon attention because of persistent criticism by human rights groups, some members of Congress and others of the conditions in which Manning had been held.

Johnson, however, told reporters at a hastily arrangement news conference on Tuesday, "The fact that we have made a decision to transfer this particular pretrial confine ... should not be interpreted as a criticism of the place he was before."

Army Undersecretary Joseph Westphal, speaking at the same news conference, acknowledged that the brig at Quantico was not designed to hold pretrial detainees for more than a few months.

"We were looking at a situation where he would need an environment more conducive for a longer detention," Westphal said.

The new facility has more space, and Manning will have a greater opportunity to eat and interact with other prisoners there, officials said. There also is a larger staff of trained mental, emotional and physical health specialists.

Lt. Col. Dawn Hilton, who is in charge of the medium-security detention facility at Leavenworth, said Manning will undergo a comprehensive evaluation there to assess whether he is a risk to his own or others' safety. The 150 inmates at the facility - including eight who are awaiting trial - are allowed three hours of recreation a day, she said, and three meals a day in a dining area.

She said the facility, which opened for pre-trial detainees in January, is designed for long-term detention. Officials say Manning's case, which involves hundreds of thousands of highly sensitive and classified documents, is complex and could drag on for months, if not years.

Manning faces nearly two dozen charges, including aiding the enemy, a crime that can bring the death penalty or life in prison.

His transfer to Leavenworth comes a bit more than a week after a UN torture investigator complained that he was denied a request to make an unmonitored visit to Manning. Pentagon officials said he could meet with Manning, but it is customary to give only the detainee's lawyer confidential visits.

The UN official, Juan Mendez, said a monitored conversation would be counter to the practice of his UN mandate.

A few days later, a committee of Germany's parliament protested about Manning's treatment to the White House. And Amnesty International has said Manning's treatment may violate his human rights.

Tom Parker, a policy director at Amnesty International, said, "The conditions that he was reported to be held in at Quantico were extremely harsh and could have damaged his mental health."

President Barack Obama and senior military officials have repeatedly contended that Manning is being held under appropriate conditions given the seriousness of the charges against him.

He is accused of leaking hundreds of thousands of documents to the anti-secrecy website WikiLeaks, including Iraq and Afghanistan war logs, confidential State Department cables and a classified military video of a 2007 Apache helicopter attack in Iraq that killed a Reuters news photographer and his driver.