Journalists Ivica Marijacic, Domagoj Margetic and Stjepan Seselj have been charged by the Hague tribunal with contempt of court for publishing protected testimonies and revealing the identity of protected witnesses who testified in the trial of General Tihomir Blaskic.
Commenting on the indictments, HND vice-president Zdenko Duka has said that the journalists "acted unprofessionally and violated the statute of the Hague tribunal".
The open letter, sent to the HND leadership by the Initiative for Freedom of the Press and Depoliticisation of the HND, says that Duka's response was completely contrary to the fundamental principles of the Journalists' Association and media freedom.
The signatories called on the HND leaders to retract their statement and respect the organisation's principles, notably to protect all journalists and freedom of the press.
"Otherwise, we the undersigned demand the unconditional resignation of the HND leadership," the letter says.