The letter was written to alert the UN secretary-general to statements by Sri Lanka's government and military that "put journalists in grave danger".
It said that in commentaries published on its website on Thursday 5 June 2008, the Defence Ministry labelled journalists critical of the war effort against Tamil rebels as "enemies of the state" and said it would take "all necessary measures to stop this journalistic treachery."
This follows comments last January by Army Commander Sarath Fonseka who labelled some journalists as traitors.
"(We) condemn these statements, which risk encouraging those who have used extreme violence against journalists and other news professionals in the country," the letter said.
The global survey of news media casualties, p