The U.S. Army says imprisoned transgender soldier Chelsea Manning was briefly hospitalized this week, though few details have been provided.

Army spokesman Wayne Hall says the 28-year-old Manning was taken to a hospital Tuesday near Fort Leavenworth and was later returned to the Kansas military base's prison, where Manning is now being monitored. Hall and other Pentagon officials didn't say why Manning was hospitalized.

Manning, formerly Bradley Manning, was convicted in military court in 2013 for sending classified information to the anti-secrecy website WikiLeaks. Manning is serving a 35-year prison sentence.

Manning's appellate attorney, Nancy Hollander, said she was unaware of the hospitalization until Wednesday and was "profoundly distressed by the complete lack of official communication about Chelsea's current situation."

A Fort Leavenworth spokeswoman declined comment, citing medical privacy laws.