Kurdish protesters, angered by years of austerity and unpaid public sector salaries, attacked several offices of the main political parties in Iraq's Kurdish north on Tuesday in a second day of violent unrest amid tensions with Baghdad.

About 1,250 protesters, mostly teachers, students, and civil servants, were out in the city of Sulaimaniya. Six were injured, regional health officials said, after the crowd was shot at with rubber bullets and sprayed with tear gas by security forces.

Acknowledging that protesters had a "legitimate right" to demonstrate, Iraq's Kurdistan Regional Government (KRG) nonetheless said the targeting of government offices and party headquarters in Sulaimaniya province was unacceptable.

"We are concerned with the uncivil actions and the violence used today in a number of cities and towns across Kurdistan," the KRG said in a statement.

It warned that relevant authorities could intervene to prevent further damage, after several people were left injured and properties damaged.

Tension has been high in the region since the central government in Baghdad imposed tough measures when the KRG unilaterally held an independence referendum on Sept. 25 and Kurds voted overwhelmingly to secede.

The move, in defiance of Baghdad, also alarmed neighbouring Turkey and Iran who have their own Kurdish minorities.

For the second day, protesters demanded that the KRG quit.

They set fire to the offices of Kurdish political parties in the towns of Koya, Kifri and Ranya. Officials have closed roads around Sulaimaniya, a Reuters witness said.

Security sources said the road between Darbandikhan and Sulaimaniya, which connects the city to southern towns where there are major protests, has been closed.

On Monday, Kurdish political offices were also set ablaze in Sulaimaniya province, including a building belonging to the ruling Kurdish Democratic Party (KDP) and one belonging to its coalition partner in government, the Patriotic Union of Kurdistan (PUK).

At least 3,000 Kurdish demonstrators had gathered in Sulaimaniya for the protests on Monday against the KRG.

Stringent economic measures taken after the Baghdad central government slashed funds to the KRG in 2014 when it built its own oil pipeline to Turkey in pursuit of economic independence have led to sporadic protests over unpaid civil servant salaries in the last three years.

After the September referendum, the Iraqi government responded by seizing Kurdish-held Kirkuk and other territory disputed between the Kurds and the central government. It also banned direct flights to Kurdistan and demanded control over border crossings.