Lawmaker Hussein al-Maliki said parliament voted to dismiss Kirkuk Gov. Najmiddin Karim based on consultations with Prime Minister Haider al-Abadi.

Iraq’s parliament on Thursday voted to dismiss the Kurdish governor of the ethnically mixed Kirkuk province, in a move that could escalate tensions ahead of a planned Kurdish referendum on independence.

To the south of Baghdad, meanwhile, militants attacked a checkpoint and nearby restaurant in the southern Thi Qar province, killing at least 45 people and wounding 83, according to provincial Gov. Yahya al-Nassiri.

Iraq’s Kurds plan to hold the vote on Sept. 25 in three governorates that make up their autonomous region as well as disputed areas like Kirkuk that are controlled by Kurdish forces but claimed by Baghdad. Late last month, Kirkuk’s provincial council voted to take part in the referendum. Iraq’s central government has rejected the polls as unconstitutional and illegal.

Lawmaker Hussein al-Maliki said parliament voted to dismiss Kirkuk Gov. Najmiddin Karim based on consultations with Prime Minister Haider al-Abadi.

Mohammed al-Karboli, another Arab lawmaker, said Mr. Karim “threatens the country’s unity and civil peace in Kirkuk.”

All Kurdish members boycotted Thursday’s session, while 187 mainly Arab and Turkmen legislators voted in favor, the two lawmakers said. The governor has the right to appeal the decision, Mr. al-Karboli added.

Oil-rich Kirkuk is home to a mix of 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.

Iraq’s Kurdish region has enjoyed a high degree of autonomy since the U.S. imposed a no-fly zone over northern Iraq after the 1990 Gulf War. It has its own parliament and armed forces, flies its own flag, and has been a close U.S. ally against IS and other militant groups. But relations with Baghdad have grown strained in recent years over oil and the disputed areas.

The attack in Thi Qar started with militants opening fire at the checkpoint and the restaurant on the main highway that links Baghdad with the southern provinces, Mr. Al-Nassiri said. That was followed by two suicide bombers, including one driving an explosives-laden car, he added.

Three policemen were among the dead and the majority of those killed were expected to be Iranian pilgrims en route to visiting religious shrines who were resting inside the restaurant, he said.

No group immediately claimed responsibility for the attack. The Islamic State group often claims responsibility for large-scale attacks targeting security forces and Shia civilians in Iraq.

Shia Muslim-dominate Thi Qar is located about 320 km southeast of Baghdad.