KIRKUK, Iraq: Islamic State militants killed at least 10 people including a local Sunni tribal sheikh in two separate attacks late on Sunday in Iraq's northern provinces of Mosul and Kirkuk, police and local officials said.

In a village near the Sunni town of Shirqat, south of Mosul, Islamists stormed the house of a tribal sheikh who led a Sunni militia that had fought against the militants, killing him, his son and two guests, police sources said.

Islamic State, which had seized control of much of northern Iraq in 2014, lost Shirqat to U.S.-backed Iraqi security forces supported by Sunni tribal fighters in 2016. However, a small number of militants are still operating in the area and are capable of launching sporadic attacks, security officials said.

In the town of Nijana, south of the oil city of Kirkuk, five members of one family were killed by militants who set up a fake security checkpoint on a main road. The family were Shi'ite Turkmens - a father who is an Iraqi soldier, his pregnant wife, his two children and his brother-in-law.

Local police said their five charred corpses were found inside the burned-out car, after the militants fled the scene. Two police officers accused Islamic State militants of carrying out the attack.

Another passer-by was also killed inside his car during the attack, said police sources.

Iraqi security forces launched an operation last month to consolidate control of the Hamrin mountain range near Kirkuk, intended to be used as a transit route for Iraqi oil trucks heading for Iran.

Security officials say two groups of insurgents are known to be operating in the area - one formed by remnants of Islamic State, the other, known as the "White Banners", new and little known.

Iraq declared victory in December over Islamic State, which had seized control of nearly a third of the country in 2014. However, the group continues to carry out attacks and bombings in Baghdad and other parts of Iraq.

Iraqi security officials have warned that they expect a new phase of guerrilla warfare from remaining Islamic State adherents.

(Additional reporting by Ghazwan Hassan in Tikrit; Writing by Ahmed Rasheed; Editing by Kevin Liffey)