A week of anti-government protests earlier this month left more than 150 people dead. Renewed demonstrations on Friday claimed the lives of another two dozen people, with forces firing live rounds and tear gas.

"We deeply regret the number, the large number of people that have been killed in these circumstances," Guterres told reporters, citing a recent report by a UN mission on the behavior of security forces in Iraq.

"According to our preliminary findings, there were, indeed, substantial violations of human rights that took place and need to be clearly denounced and condemned," Guterres said.

He did not specify how the security forces might be punished.

The report published Tuesday by the UN Assistance Mission for Iraq, covering events from October 1-9, concluded that "serious human rights violations and abuses have been committed in the context of the demonstrations in Iraq."

Iraqis have been protesting over poverty, unemployment and a lack of basic services.

Almost all of those killed in early October were protesters and most died in the capital Baghdad, the Iraqi government said.