Two opposition parties, the Gorran and the Kurdistan Islamic Group (Komal), have withdrawn from Iraq's semi-autonomous Kurdistan Regional Government (KRG), party sources said.
The withdrawals came Wednesday after two days of violence in the region, as Kurdish demonstrators protest years of austerity measures and unpaid public sector salaries.
Regional tensions escalated after the central government in Baghdad imposed stringent measures due to the KRG's holding of an independence referendum, on September 25, in which the Kurds voted overwhelmingly to secede.
The decision to withdraw came in defiance of Baghdad and alarmed neighboring Iran and Turkey, which have sizable Kurdish minority populations.
The opposition parties have said they support the demands of the protesters but urged calm after two days of deadly protests.
At least three people have been killed and more than 80 others injured since Tuesday in clashes with Kurdish security forces, local officials said.
On Monday and Tuesday, protesters also attacked several offices of the main political parties in northern Iraq's Sulaimaniya province.
There were no major protests Wednesday in Sulaimaniya, but security forces from the regional capital of Irbil have been deployed in the area, enforcing curfews after Tuesday's violence.
Kurdish Prime Minister Nechirvan Barzani said Tuesday while on an official visit to Germany he understood the protesters' frustrations, but that torching the offices of political parties was "not helpful."
The United Nations Assistance Mission for Iraq said Wednesday it was "deeply concerned" about the unrest and issued a plea for restraint.
"The people have a right to partake in peaceful demonstrations, and the authorities have the responsibility of protecting their citizens, including peaceful protesters," UNAMI said.
The U.N. mission also urged the KRG to respect the rights of the media after Kurdish security forces took a private Kurdish television station, NRT TV, off the air.