The ethnically mixed city of Kirkuk, located approximately 250 kilometres (155 miles) north of Baghdad, is regarded by Kurds as part of their ancestral homeland.

Eight months after Iraq's top Shiite cleric Grand Ayatollah Ali al-Sistani summoned volunteer fighters into battle against the ISIS militants, his call has manifested itself in one of Iraq's most hotly-disputed territories.

Shiite militias, locally known as Popular Mobilisation Forces, have come to the northeastern Iraqi city, despite Kurdish repudiation, insisting it's their religious obligation to defend it.

In a statement last week, Massoud Barzani, the president of the Kurdish Regional Government, said that fighters with the Hashd Al-Shaabi militia group were "prohibited under any circumstances" from entering Kirkuk.

On the frontline just outside the city, Ja'far Mustafa, commander of peshmerga forces in the Kirkuk province, insisted there were no militias in or outside the city.

"It's not true, it's far from reality. This area is protected by peshmerga forces and there are no any other forces here. And the peshmerga don't need any other forces here, apart from the coalition air strikes," he said.

Mustafa said that flags of the Shiite militias that can be seen just outside Kirkuk were put up there by Shiite residents in the area, not the militias.

But The Associated Press found many Shiite militias on the fringes of Kirkuk, protecting the frontlines alongside the peshmerga troops.

They were singing: "Daesh, run Daesh, because of an order from al-Sistani", referring to the Shiite Grand Ayatullah and spiritual leader of Iraqi shiats.

Shakir Mahmour, a Shiite militia commander pointed out territory held by the ISIS group and down the frontline.

"Peshmerga are over there until the bridge and they are also on this side and we mingle with them," he said.

Abu Qassim, commander of the Hashd al-Shaabi militia group in Kirkuk, said the peshmerga troops need the help of the militias, as they're not well trained.

Partnerships in Kirkuk provoke sensitivities among Kurds who fear their claim over the city may once again be threatened.

Some Arab residents living in the city say that whoever provides security is welcome. "The most important thing is that they have to take care of the people and provide security, said Yassin Ahmed, an Arab citizen of Kirkuk.