A former contract linguist for the Federal Bureau of Investigation (FBI) pleaded guilty on Thursday to leaking classified documents to an Internet blogger, the Justice Department said.

Shamai Kedem Leibowitz, 39, of Silver Spring, Maryland, pleaded guilty in a federal court in Greenbelt, Maryland, to one count of disclosing classified information to an unauthorized person, the department said in a statement.

Leibowitz, also known as Samuel Shamai Leibowitz, acknowledged handing over five FBI documents concerning the communication intelligence activities of the United States to the blogger, who was not identified.

The blogger then published information online derived from the documents, which were classified as "secret," the Justice Department said.

The department said prosecutors and Leibowitz had agreed that a 20-month prison term was the "appropriate sentence" in the case. The plea agreement and sentence remain subject to the approval of the court.

"The willful disclosure of classified information to those not entitled to receive it is a serious crime," said David Kris, assistant attorney general for national security.

"Today's guilty plea should serve as a warning to anyone in government who would consider compromising our nation's secrets."

According to the plea agreement, Leibowitz was employed by the FBI as a contract linguist from January through August of this year.

He held a top secret security clearance and had access to classified documents on communication intelligence activities.

"As a trusted member of the FBI ranks, Leibowitz abused the trust of the FBI and the American public by using his access to classified information for his own purposes," said special agent in charge Richard McFeely.