Islamic State militants struck at Kurdish forces southwest of the Iraqi city of Kirkuk on Friday, while bombs in Kirkuk, Baghdad, Samarra and Ramadi killed at least 27 people.
The Sunni Islamists have often battled Iraqi security forces and Shiite militias further south and west, but attacks in and around Kurdish-controlled Kirkuk have been less frequent.
Oil rose above $49 a barrel on Friday because of the violence in the oil-rich region.