State prison officials in Maryland want to impose the nation's first total ban on letters being sent to prisoners at state facilities.

They want to limit any mail state inmates get to postcards and official legal correspondence. The reason: Suboxone, a highly addictive drug that can be hidden inside envelopes or soaked into paper, is flooding into Maryland's prisons.

Emergency regulations to ban nonofficial letters were proposed last month to a state legislative panel by the Maryland Department of Public Safety and Correctional Services. Now the American Civil Liberties Union is pushing prison officials to reconsider.

Prison authorities report intercepting more than 3,000 hits of Suboxone behind bars last year, roughly 44 percent of which were found in incoming letters.