"The violation of Iraqi sovereignty and rule of law by armed militias harms all Iraqis and their country," Price said, two days after two Iraqis were killed during demonstrations by thousands of people in Baghdad.

Another 28 people were injured in the protests, which were held to demand justice over a wave of deadly attacks on pro-democracy activists and journalists.

The following day, Iraqi police separately arrested a senior official in an Iran-backed armed group on suspicion of orchestrating the killing of a prominent pro-democracy activist amid a wave of murders of activists and journalists that started in 2019.

"We welcome every effort by the government to hold accountable the militias, thugs, and vigilante groups for their attacks against Iraqis exercising their right to freedom of expression and peaceful assembly as well as for their assault on the rule of law," Price said.

"The United States is outraged that peaceful demonstrators who took to the streets to urge reform were met with threats and brutal violence," Price added.

Killings, attempted murders and abductions have targeted more than 70 activists since a protest movement erupted against government corruption and incompetence in 2019.

Since the fall of dictator Saddam Hussein in the US-led invasion of 2003, political parties have controlled life in Iraq and corruption has plagued state institutions.