Ireland's largest newspaper group says its reporters covering the Dublin gang war are receiving death threats from criminals because of their work.

Thursday's reported threats against two unidentified journalists from Independent News and Media come nearly 20 years after a crime reporter for the group's Sunday Independent newspaper, Veronica Guerin, was shot to death by members of a Dublin drug-trafficking gang she was investigating.

Two men have been killed and two wounded in tit-for-tat attacks since Friday.

Prime Minister Enda Kenny and other Irish leaders condemned the threats. Kenny said: "In any self-respecting society, journalists must be afforded the freedom to go about their jobs without fear of reprisal."

Ireland's National Union of Journalists urged reporters covering the story "to remain vigilant and mindful of their safety."