Iraqi security forces opened fire on protesters in the southern city of Basra on Thursday while dispersing them, killing three, according to a medical source.
Dozens of people were also injured by live bullets, the source said on condition of anonymity due to restrictions on speaking to the media.
At least 260 people have been killed and thousands injured in a second wave of anti-government demonstrations in Iraq since last week.
More than 230 people were killed in the first wave of protests in October.
Popular anger has been simmering in Iraq in recent years due to rising