Forty-four Iraqi MPs have announced their resignation over violence in Anbar province, just days after a deadly raid on the home of a Sunni lawmaker in the area.
Fighting erupted when police broke up a Sunni Muslim protest camp on Monday, leaving at least 13 people dead, police and medical sources said.
Four people died on Tuesday in clashes between Iraq's security forces and gunmen in Ramadi, following the forced closure of the site.
The camp has been an irritant to Prime Minister Nouri al-Maliki's Shia-led government since protesters set it up a year ago to demonstrate against what they see as marginalisation of their sect.
Maliki has repeatedly vowed to remove the camp and accused protesters of stirring strife and sheltering fighters linked to al-Qaeda.
The MPs who stepped down after the latest bout of violence demanded "the withdrawal of the army... and the release of MP Ahmed al-Alwani," a Sunni of the Iraqiya bloc who was arrested during a deadly raid on Saturday.
Prominent Sunni politician Saleh al-Mutlaq called for all legislators from Iraqiya to withdraw from the political process, saying it had hit a "dead end".
"Elections in this atmosphere would be settled in advance, therefore we should raise our voices high and say the political process cannot proceed in this way," he told reporters.
Tensions have been rising over the past few weeks in Anbar, a province that makes up a third of Iraq's territory and is populated mainly by Sunnis.
Police said the clashes on Monday broke out when armed men opened fire on police special forces trying to enter Ramadi, the city where the protest camp is located.
We hold the government of Nouri al-Maliki responsible for the bloodshed and the fighting.
Shooting and blasts were heard in parts of the city. The assailants destroyed four police vehicles and killed at least three policemen in the north of Ramadi, one police source said.
The bodies of 10 other people killed in the clashes were brought into Ramadi's morgue, hospital and morgue sources told Reuters news agency.
Tribal leader Mahmoud Abdel Aziz, meanwhile, accused the army of firing on unarmed civilians.
"We hold the government of Nouri al-Maliki responsible for the bloodshed and the fighting," he said.
The fighting spread to the nearby city of Fallujah, where police Captain Omar Oda said armed men burned military vehicles during clashes with security forces.
Maliki's spokesman, Ali Mussawi, said military sources confirmed that tents at the protest site had been removed and the highway towards neighbouring Jordan and Syria reopened.
This was done "without any losses, after al-Qaeda and its members escaped from the camp to the city, and they are being pursued now," Mussawi told AFP.
The sprawling protest site on the highway outside Ramadi, where the number of protesters ranged from hundreds to thousands, included a stage from which speakers could address crowds, a large roofed structure and dozens of tents.
Sunni politicians arrested
Protests broke out in Sunni Arab-majority areas of Iraq late last year after the arrest of guards of then-finance minister Rafa al-Essawi, an influential Sunni Arab, on terrorism charges.
The arrests were seen by Sunnis as yet another example of the Shia-led government targeting one of their leaders.
In December 2011, guards of vice president Tariq al-Hashemi, another prominent Sunni politician, were arrested and accused of terrorism. Hashemi fled abroad and has since been given multiple death sentences in absentia for charges including murder.
He had insisted he was still the legitimate vice president, but on Monday he announced his resignation and called on all Sunni members of parliament join him.
"Legally I was still the vice president of the republic. But today I add my voice to my people who have risen up in Anbar," he told Al Jazeera.
"I stayed in this position until now because it was necessary to challenge and unite the Sunnis. They needed a rallying cause. But enough is enough."