Islamic State (IS) militants have mounted a ferocious counter-attack in north Iraq, killing a minimum of 19 individuals in and around town of Kirkuk.
They attacked government buildings, killing at least six cops, and an influence station under construction, where thirteen workers died, officials say.
Twelve IS fighters additionally reportedly died and fighting appears to be continuing.
Government and Kurdish forces began a long-awaited operation against the IS capital in Iraq, Mosul, on Monday.
Mosul lies 170km (one hundred and five miles) to the north-west of Kirkuk, a multi-ethnic town claimed each by Iraq's central government and the Kurds.
Government forces said on Friday they'd regained control of a additional 2 villages - al-Awaizat and Nanaha - south of Mosul, evacuating 65 displaced families and killing 15 IS militants.
Hours once the initial assault, witnesses in Kirkuk said gunfire could still be heard and militants were walking brazenly through the streets. Initial reports steered as several as sixteen civilians had been killed.
Local media say a state of emergency has been declared and Friday sermons have been cancelled as mosques stay closed.
A news agency affiliated to IS said fighters had broken into Kirkuk's city hall and seized a central hotel however officials denied this.
District police chief Brig Gen Sarhad Qadir told the BBC suicide bombers and different IS fighters had attacked three police buildings and therefore the headquarters of a political party in Kirkuk.
"All of the militants who attacked the police emergency building and also the recent building of the Kirkuk police directorate are killed but a range of other militants are still in Dumez district," he said.
The governor of Kirkuk, Najm al-Din Karim, insisted that Kurdish Peshmerga fighters and counter-terrorism forces were utterly in management of the situation.
He blamed the attack on IS sleeper cells.
"As a result of of the continued Mosul offensive, they will want to form a situation where forces would be withdrawn from there and the main focus shifted to Kirkuk," Mr Karim told Kurdish news agency Rudaw.
"Additionally as a result of they are being defeated in Mosul, they wish to boost their morale with these types of actions."
Five Iranian workers are believed to be among the dead in the attack on the ability plant to the north of Kirkuk, Iraq's electricity ministry said.
Seven other staff and five police guards were wounded.
The ability plant, which continues to be under construction, is being designed by an Iranian company.
