Ms Hartmann described top-level talks about the Bosnia peace deal
A former spokeswoman for the United Nations war crimes court in The Hague has been charged with revealing confidential information.
The tribunal accuses Florence Hartmann - who is French - of contempt of court in relation to the trial of the late Serbian leader Slobodan Milosevic.
She "knowingly and wilfully" disclosed confidential information, violating an appeals chamber order, the court says.
Ms Hartmann has been summoned to appear before the court on 15 September.
She could face seven years in jail or a fine of 100,000 euros (£80,000; $150,000) if found guilty.
The two charges relate to a book and an article Ms Hartmann published after leaving her post as spokeswoman for the former chief war crimes prosecutor Carla del Ponte in 2006.
Slobodan Milosevic died at the tribunal's detention centre near The Hague in March 2006 before his trial had ended.
A statement from the International Criminal Tribunal for the former Yugoslavia (ICTY) on Wednesday said Ms Hartmann "knew that the information was confidential at the time disclosure was made, that the decisions from which the information was drawn were ordered to be filed confidentially, and that by her disclosure she was revealing confidential information to the public".
The book, called Peace and Punishment, was published in September 2007, and the article for the Bosnian Institute in January 2008.
In her book, Ms Hartmann claimed that Russia shielded the Bosnian Serb wartime leader Radovan Karadzic from arrest in 1997.
Mr Karadzic, arrested last month in Belgrade, is due to appear before the tribunal for the second time on Friday. He is required to enter a plea to charges of war crimes and crimes against humanity.