The Islamic State has evacuated key checkpoints in the southwest of Kirkuk in Iraq, a local source from the region said on Sunday.

Iraq's Ministry of Defence had revealed on Saturday that it would redeploy its troops to Kirkuk for a campaign to retake the Al-Hawija district from the Islamic State. The Iraqi military will be aided by the Iraqi Federal Police (IFP) in this major operation.

But the source from Kirkuk told Alghad Press that militants were seen hurriedly vacating their strongholds before the imminent assault. "Tens of Islamic State fighters collectively evacuated several checkpoints in Hawija, southwestern Kirkuk, under mysterious circumstances," said the source.

He also added that the militants "withdrew from sprawling regions on borders with Salahuddin province located near to oil fields."

The Iraqi military and the IFP were recently withdrawn from the now liberated town of Tal Afar in the Nineveh Province but arrived in Mosul's Al-Qayyarah district on Saturday ahead of marching towards Al-Hawija. "Most of the troops who participated in the liberation of Tal Afar will participate in the Hawija campaign", said First Lieutenant Fayeq Numan al-Salim speaking to Anadolu Agency. It is also believed that the Hashd al-Shaabi force, a Shia military group, will also lend their arms to the Iraqi military in fighting the Islamic State.

Kurdistan president issues warning

Kurdistan Region President Masoud Barzani said earlier that any attempts to take over Kirkuk will be met with "strong reaction' from Kurdish forces. The Kirkuk province is a subject of dispute over its sovereignty between Kurdistan and the Iraqi government,

"Kirkuk is Kurdish...any force that thinks of taking Kirkuk by force will be faced by the whole people of Kurdistan.

We will defend it by the last one of us," said Barzani as quoted by several Iraqi news websites. "Kirkuk is not only Kurdish, it is for Kurds, Arabs and Christians...we shall make it a model of coexistence."

Kurdish referendum

A referendum has been scheduled on September 25 this year to determine the status of Iraqi Kurdistan as an independent nation.

Barzani's comments came after a senior Shia military leader threatened to consider Kurdistan as the "enemy" if it included Kirkuk as a voting district during the referendum.

The Shia leader is believed to be Qais al-Khazali who is the commander of the Asa'ib Ahl al-Haq. al-Khazali claims that Kurdistan's inclusion of Kirkuk is a "serious matter that needs an official and decisive response."