(Reuters) - U.S. soldier Chelsea Manning, imprisoned for handing over classified files to pro-transparency site WikiLeaks, was hospitalized, her attorney said on Wednesday, after media reports that Manning had attempted to commit suicide.

The Army confirmed Manning, 28, who was born male but identifies as a woman, had been released back into custody from the hospital, American Civil Liberties Union attorney Chase Strangio said. Manning's medical condition was not released.

Manning was taken to a hospital near the U.S. Disciplinary Barracks at Fort Leavenworth, Kansas, early on Tuesday, U.S. Army spokesman Colonel Patrick Seiber said.

CNN, citing Seiber and an unnamed official, reported that she was taken to a hospital after an apparent attempt to take her own life.

"Reports of Chelsea's suicide attempt are unconfirmed," Strangio wrote on Twitter. "We just know that she was taken to the hospital and are trying to learn more."

Seiber said that officials continue to monitor the inmate's condition.

Attempts to reach the military correctional facility where Manning is imprisoned were not successful.

One of Manning's attorneys, Nancy Hollander, said in a statement on Wednesday that she was outraged over the release of her client's confidential medical information to the news media. Hollander also said the Army failed to connect Manning with her lawyers for a planned phone call on Tuesday, and the earliest Army officials could accommodate a call was Friday morning.

"We call on the Army to immediately connect Chelsea Manning to her lawyers and friends who care deeply about her well-being and are profoundly distressed by the complete lack of official communication about Chelsea's current situation," Hollander said.

Manning, a former intelligence analyst in Iraq, is serving a 35-year sentence after a 2013 military court conviction of providing more than 700,000 documents, videos, diplomatic cables and battlefield accounts to WikiLeaks. It was the biggest breach of classified materials in U.S. history.

Among the files that Manning turned over to WikiLeaks in 2010 was a gunsight video of a U.S. Apache helicopter firing at suspected Iraqi insurgents in 2007. A dozen people were killed, including two Reuters news staff.

Manning in May appealed to an Army court to overturn her court-martial conviction.

Manning's lawyers contend she was held in unlawful pretrial detention for almost a year and that she was excessively charged so she would be exposed to undue punishment. They also argue that the trial judge considered evidence that was not related to the offenses.

(Reporting by Laila Kearney in New York and Eric M. Johnson in Seattle; Editing by Bernard Orr)