Iraq's parliament meanwhile rejected the referendum in a non-binding resolution, calling it "unconstitutional" and a threat to the country's unity.
Iraq's Kurds plan to hold the referendum on Sept. 25 in three governorates that make up their self-ruled region as well as disputed areas that are controlled by Kurdish forces but claimed by Baghdad, including the oil-rich province of Kirkuk.
Masoud Barzani, the president of Iraq's Kurdish region, insisted that holding the referendum in Kirkuk is "entirely legal."
"Kirkuk will remain as safe and secure as it is now, kept safe by the peshmerga," Barzani said, referring to the Kurdish forces that control the city. "We will not compromise Kirkuk's identity. We would rather give up our own rights than to compromise the rights of the ethnic minorities that live here."
Kirkuk is home to Arabs, Kurds, Turkmen and Christians. Kurdish forces took control of the province and other disputed areas in the summer of 2014, when the Islamic State group swept across northern and central Iraq and the Iraqi armed forces crumbled.
Iraqi and Kurdish forces have driven IS from most of the country over the past two years, but now appear to be girding for a new conflict over the spoils.
The parliament resolution states that the referendum is a "threat to Iraq's integrity, which is guaranteed by the constitution... in addition to the civil peace and the regional security." It called on the central government to "shoulder its responsibly to protect the unity of Iraq and to take all necessary measures to preserve that unity."
All Kurdish lawmakers boycotted Tuesday's session, while Arab lawmakers voted in favor, said lawmaker Mahmoud al-Mashhadani, who attended the session. A breakdown for the vote was not immediately available.
During his weekly press briefing, Iraqi Prime Minister Haider al-Abadi again rejected the referendum and called on Kurdish leaders to come to Baghdad for dialogue.
Turkey and Iran, concerned about separatist leanings among their own Kurdish populations, are also opposed to the referendum, and the U.N. mission to Iraq has said it will not be "engaged in any way or form" in the vote.
In Kirkuk, Barzani addressed growing fears that the independence vote could lead to violence between forces aligned with Baghdad and those loyal to the Kurdish region.
"We have no intention to start a fight," he said. "But we have the right to defend ourselves. Those who launch a war have to expect a response."
Al-Saleh reported from Baghdad. Associated Press writer Emad Matti in Kirkuk contributed to this report.
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