Kirkuk, Iraq: Gunmen wearing suicide vests attacked government targets in the Kurdish-controlled city of Kirkuk and killed 16 at an Iranian-run construction site further north on Friday as troops advanced on jihadist bastion Mosul.
There was no immediate claim for the attacks but nearly all such raids have been carried out by the Islamic State group, which is attempting to defend its last major Iraqi stronghold against a massive military offensive.
In one attack, three bombers infiltrated a power plant being built by an Iranian company near Dibis, a town about 40 kilometres (25 miles) north-west of Kirkuk, the mayor said.
"Three suicide bombers attacked the power plant at around 6:00 am (0300 GMT), killing 12 Iraqi administrators and engineers and four Iranian technicians," Dibis mayor Abdullah Nureddin al-Salehi told AFP.
A police lieutenant colonel confirmed the casualty toll.
The mayor said the attack led to clashes with security forces, who managed to kill one of the bombers before he detonated his vest. The other two blew themselves up once they were surrounded, he said.
Hours earlier, a commando of suicide bombers armed with rifles attacked multiple locations in Kirkuk, an ethnically divided city 240 kilometres (150 miles) north of Baghdad, security sources said.
A Kurdish intelligence officer said four suicide bombers attacked the main police headquarters in the city at around 3.00 am (2400 GMT Thursday).
"The security forces managed to shoot one of them dead, the other three blew themselves up," he said.
Several other targets in the south of the city were attacked by what the officer said were members of IS, sparking clashes with security forces that were still ongoing five hours later.
A Kirkuk official told AFP that a total curfew was slapped on the city.
Local Kurdish television channel Rudaw aired footage showing black smoke rising over the city as extended bursts of automatic gunfire rang out. The TV, however, quoted Kirkuk Gov. Najmadin Karim as saying that the militants have not seized any government buildings.
There were no immediate reports of casualties.
The attack comes as the Iraqi government and Kurdish forces are making a major push to drive Islamic State militants from Iraq's second-largest city of Mosul.
Kirkuk is an oil-rich city some 290 kilometers (180 miles) north of Baghdad and south-east of Mosul that is claimed by both Iraq's central government and the country's Kurdish region. It has long been a flashpoint for tension and has been the scene of multiple attacks by Islamic State militants.
Kemal Kerkuki, a senior commander of Kurdish peshmerga forces west of Kirkuk, said the town where his base is located outside the city also came under attack early on Friday. He said the base is now under control.
He said IS maintains sleeper cells in Kirkuk and the surrounding villages, and that a group of IS fighters tried to attack a power station in Dibis village west of Kirkuk with light arms and a suicide bomber.
IS also claimed an attack on the power station, saying that its fighters had stormed the facility and killed all security forces stationed there.
Kerkuki said he believes the attackers infiltrated Kirkuk posing as displaced civilians. The city has absorbed hundreds of thousands of displaced people from the neighboring provinces since IS first overran wide stretches of northern and western Iraq in the summer of 2014.
"Many of (the displaced civilians), I'm sure they are working with Islamic State," Kerkuki said, using an alternative acronym for the Islamic State group. "We arrested one recently and he confessed (he was part of a sleeper cell)."
Iraqi and Kurdish forces backed by US-led coalition support launched a multi-pronged assault this week to retake Mosul and surrounding areas from IS. The operation is the largest undertaken by the Iraqi military since the 2003 US-led invasion.
Iraqi officials said they had advanced as far as the town of Bartella, 15 kilometers (9 miles) from Mosul's outskirts, by Thursday.
Updated Date: Oct 21, 2016 13:20 PM