About 70,000 Kurds converged on local government headquarters in Sulaymaniya in northeastern Iraq calling for the oil-rich city of Kirkuk - outside the Kurdish region - to become the capital of a Kurdish nation.
Banners also called on the two main Kurdish parties, the PUK and the KDP, to bury their rivalry and unite to present a stronger Kurdish challenge for independence.
The move appears to be part of efforts to build a united front before elections scheduled for January, when Kurds will have a chance to vote not only in Kurdish regional elections, but in a national poll for an Iraqi National Assembly.
Smaller demonstrations were reported in the northern Kurdish town of Dohuk. In Kirkuk itself – a tense city with rival populations of Arabs, Kurds and Turkmen – about 2000 Kurds held a demonstration.
In Sulaymaniya, several protesters carried banners reading "Kurdistan means nothing without Kirkuk".
The Kurds rebelled against the
government of Saddam Hussein
Kurds, who make up about 20% of Iraq's population, have had effective autonomy in the north of Iraq since the 1991 Gulf War, but have been pushing for further independence since the overthrow of Saddam Hussein.
Since Saddam's fall, thousands of Kurds and Turkmen have returned to Kirkuk and surrounding areas in efforts to regain control of what they say are ancestral lands. Many Arabs have since been driven away from the region in a wave of coercion and violence.
The city of about one million people has been tense for more than a year, but the situation has worsened in the run-up to the January elections. Some analysts fear the issue of Kirkuk could provoke civil war.
The call for Kirkuk to be made the capital of an autonomous Kurdistan is also particularly sensitive for Iraq's central government.
If Kirkuk is made the capital, Kurds may also call for Kirkuk's huge oil revenues to be only directed to them.