"Hands off journalists," said a banner carried by a reporter. "Report Card 2006-2007: Eight journalists killed," said another placard.
Activists at the rally accused the government of imposing unofficial censorship in the northern peninsula of Jaffna where two Tamil newspaper employees were shot dead last year by unidentified gunmen.
In its 2006 review, the Paris-based media watch dog, Reporters Without Borders, said that decades of fighting between Sri Lankan troops and Tamil Tiger rebels had a major fallout on the freedom of the media.
"The dormant war between security forces and the Tamil Tigers (LTTE) has had harmful consequences for the safety of journalists, particularly Tamils," Reporters Without Borders said.
Journalists from the majority Sinhalese community too have been either killed, beaten or intimidated for their coverage of the conflict.
"Murders, arrests, threats and bombings have again become the daily lot for many reporters, particularly in the north and east of