French journalist Florence Hartmann imprisoned alongside war criminals in The Hague for claims in 2007 book

Writer accused of 'contempt of court' for claiming court withheld documents relating to the Srebrenica massacre

Florence Hartmann was arrested on Thursday as she attended a vigil outside The Hague (The Hague)

An international war crimes tribunal has jailed a French journalist over a book she wrote in 2007 about its investigation into a massacre in the Bosnian war.

Florence Hartmann, a former correspondent for Le Monde, was seized by United Nations police outside The Hague court in the Netherlands on Thursday.

She is being held for contempt of court, after revealing the tribunal withheld documents on the Srebrenica massacre from its sister organisation, the International Criminal Court.

Ms Hartmann, who covered the conflict in Bosnia as a reporter, was originally ordered to pay a €7,000 fine after her conviction in 2009.

But this sentence was upgraded to seven days imprisonment in 2011 when the fine remained unpaid.

Her lawyer, Guénaël Mettraux, told The Guardian she was being held solitary isolation with lights on 24 hours a day and checks every 15 minutes.

He said: “A journalist is being detained in conditions – isolation, segregation, suicide watch – that were supposed to have been created for war criminals. It is incomprehensible.

“I filed three motions yesterday [Thursday], one of which sought to have her granted early release no later than two-thirds of her sentence, as has been accorded to war criminals convicted by the courts in The Hague and Rwanda. I’ve asked of the same to be done for a journalist, and this would mean her being released on Tuesday.

“But the problem is that there is literally no one at the detention unit who can address my inquiries, and my application will not be addressed until after the Easter break.”

The Guardian reported Ms Hartmann was approached outside the tribunal on Thursday as she joined Bosnian survivors and families to wait for the verdict on former Bosnian Serb leader Radovan Karadžić.

A notice on the tribunal’s website says: “The Mechanism [tribunal] arrested today at its premises in The Hague Ms Florence Hartmann, executing an outstanding arrest warrant issued in November 2011 by the Appeals Chamber of the International Criminal Tribunal for the former Yugoslavia (ICTY).”

Ms Hartmann received the contempt of court conviction after her book Paix et châtiment (Peace and Punishment) claimed the tribunal had documents which proved Serbian complicity in the Srebrenica massacre in 1995.

The massacre, one of the darkest moments of the Bosnian conflict, saw almost 8,000 Muslim Bosniaks murdered in and around the town of Srebrenica.

The enclave had been a desginated “safe zone”, where many Muslims had fled seeking protection from the UN, but was overrun by Bosnian Serb forces.

Ms Hartmann claimed in her book that the tribunal had kept the documents a secret from the International Criminal Court, which was carrying out its own investigation. She did not reveal the contents of the documents.

The cells where the journalist is being held are the same as those used to detain notorious war criminals for their participation in various genocides, including Rwanda, Sierra Leonne and Bosnia.

Karadžić, nicknamed the Butcher of Bosnia, was sentenced to 40 years imprisonment on Thursday.