Two people have been killed and 40 wounded after police shot at a crowd of protesters in Kurdistan, northern Iraq.
Hundreds of young men, chanting slogans against corruption and high unemployment, tried to storm the local government offices in Sulaimaniya.
There have been a string of protests in cities across Iraq. On Wednesday, three people were killed in clashes with police in the southern city of Kut.
Iraqi Prime Minister Nouri al-Maliki has appealed for calm.
"I welcome those who demonstrate peacefully for their legitimate rights, but I am not in favour of those who exploit those claims to incite riots," he told a news conference in Baghdad.
"The perpetrators will be brought to court and they will be punished," he added.
The protests in Iraq come amid a wave of unrest sweeping through the Middle East and North Africa.
An advisor to the Kurdish regional government, Tarek Jawhar, told the BBC that hundreds of young men marched towards the local offices of the Kurdistan Democratic Party (KDP) of regional President Massoud Barzani.
Witnesses said they were chanting: "The corrupt must face justice."
Police started shooting when some people tried to storm the building, resulting in the deaths of two young men, Iraqi officials said.
The KDP along with the Patriotic Union of Kurdistan have controlled the oil-rich autonomous region in the north of Iraq for several decades.
Elsewhere in the country, thousands of Iraqis - angry about a lack of basic services such as electricity and clean drinking water - have taken to the streets in recent weeks.
Demonstrations have been held in the oil hubs of Basra and Kirkuk, as well as other smaller towns, but have not resulted in any deaths or injuries.
Thursday's protest and a similar rally in Kut on Wednesday were Iraq's most violent since a wave of Arab revolts broke out last month that have toppled the presidents of Tunisia and Egypt.