Iraq's government will take "necessary measures" to preserve national unity, prime minister Haider Al Abadi said on the eve of a controversial independence referendum in the country's Kurdish region.
"To take a unilateral decision affecting the unity of Iraq and its security, and the security of the region, with a referendum on separation is unconstitutional and against civil peace," Mr Al Abadi said on Sunday.
"We will take the necessary measures to preserve the unity of the country," he said, without specifying what action his government might take. "We won't engage with the referendum or its results."
Mr Al Abadi had warned earlier of military intervention if the referendum led to violence.
The semi-autonomous Iraqi Kurdistan region is holding the vote despite pressure from Baghdad and the international community, who have warned that it would destabilise the region and affect the fight against ISIL in which Iraqi Kurd forces have played a key role.
The Iraqi Kurd president on Sunday called for people to take part in the vote peacefully and again accused Baghdad leaving the Kurds no option.
"We have tried our best to find a solution with Baghdad with the help of international community but Baghdad's central government has forced us to take this measure," Masoud Barzani said.
"The partnership with Baghdad has failed and we will not return to it," he said in Erbil, capital of Kurdistan region.
Relations between Baghdad and Erbil started to disintegrate when "Iraq violated the constitution and when it cut our budget in 2014", he said.
Wisdom has been in short supply during ill-conceived referendum campaign
Mr Barzani dismissed fears that the referendum could have wider repercussions, saying it was not being held "to draw new borders" and that Iraqi Kurds "will respect laws on international boundaries".
The vote received backing from Mr Barzani's Kurdish Democratic Party and the Patriotic Union of Kurdistan (PUK), the two main parties in Kurdistan Regional Government, and the Kurdistan Islamic Union, at a meeting earlier on Sunday.
Hemin Hawrami, a senior aide to Mr Barzani, said the parties had also agreed that the referendum would go ahead in the multi-ethnic city of Kirkuk, which is claimed by the Kurds but is not part of the Kurdistan region. The PUK was earlier divided over whether the vote should be held in the city, which has been controlled by Kurdish forces since they recaptured it from ISIL in 2014.
Mr Barzani said Monday's referendum vote would be "the first step in a long process to negotiate independence".
"The international community will accept the reality" of an independent Kurdistan, he said.
Although Kurds are confident of a vote in favour of independence, some fear the possible consequences.
"My heart says 'yes' for the referendum, but my brain says no, unity is everything," said Mehvan Abdalla, a doctor in Erbil. "But on the other hand Baghdad has violated the Iraqi constitution by cutting off 17 per cent of oil revenue that constitutionally should go to Kurdistan."
He said prime minister Al Abadi would not allow Iraq to break up on his watch.
"Kurdistan is trapped by land around all its borders with no sea or port, so it could be bottle-necked, squeezed out and starved if enemies wish. Nothing will change much no matter what the result is."
Sara Ahmed, a law student at the University of Duhok, said she was certain the referendum would result in a yes vote.
"This has been a dream for all Kurds to achieve independence and to finally say that we belong to a state," she said.
"However, we fear of what will happen after Monday's vote. We fear for our fate."
Iran and Turkey, which border the Iraqi Kurdistan region, strongly oppose the referendum for fear it could stoke separatist movements among their own Kurdish populations. Iran closed its airspace to flights from the Kurdistan region on Sunday and has warned that it will close its land borders if the vote takes place.
Iranian forces also began "war games" involving artillery, armoured and airborne units in the Oshnavieh region near the border with Iraqi Kurdistan that the state broadcaster IRIB said were part of annual events to mark the beginning of the 1980-1988 war with Iraq. Clashes with Iranian Kurdish militant groups based in Iraq are fairly common in the area. Turkey has been holding military drills near its border with the Kurdish region since last week.
The United States, Iraqi Kurdistan's main backer, reiterated its opposition to the referendum in call between secretary of state Rex Tillerson and Mr Al Abadi on Saturday after Mr Barzani announced that it would go ahead.
Mr Tillerson expressed Washington's concerns and offered its support for "maintaining the unity of Iraq", Mr Al Abadi said on his official Twitter account.