Iran's Foreign Ministry has condemned an Islamic State assault in Iraq's northern province of Kirkuk and says four Iranians were killed in that attack.

The official IRNA news agency quoted ministry spokesman Bahram Ghasemi as saying that another three Iranians were wounded in the assault.

IS launched a wave of coordinated attacks in an around the northern Iraqi city of Kirkuk early on Friday that appeared to be aimed at diverting security forces from a massive offensive underway around the IS-held city of Mosul.

The police chief in a town north of Kirkuk says IS militants attacked a power plant there, killing 11 workers, including two Iranians, before blowing themselves up. It was not immediately clear if Iranians were targeted in other attacks.