The tribes’ chiefs signed a joint agreement that was announced in a press conference on Thursday.

“We signed the agreement to stand united for Kirkuk’s salvation regardless of ethnic or religious differences,” Osman Abdul-Karim, Zangana tribe’s chief, said.

“We stand together against ISIL, which uses a religious cover to divide Iraq,” Ismail Al-Hadidi, Kirkuk’s former vice governor, said.

Iraqi government troops and Kurdish forces are fighting against ISIL, supported by a U.S.-led coalition that has been conducting airstrikes against the terrorist group for five months.

Iraq has been gripped by a security vacuum since June 2014 when ISIL stormed the northern province of Mosul and declared what it calls a “caliphate” in Iraq and Syria.

In other news, an Iraqi woman sought in a prisoner swap with ISIL militant group is still in Jordan, a government minister has said.

"Sajida al-Rishawi is still in Jordan," Information Minister Mohamed al-Momani told a press conference on Thursday.

He said Jordan was seeking guarantees from the ISIL that captured Jordanian pilot Moaz al-Kasasba was still alive before announcing a prisoner swap.

Al-Kasasba was captured by the militant group after his fighter plane crashed in the Syrian city of Raqqa last December.

On Wednesday, al-Momni said Jordan was prepared to exchange al-Rishawi – who was sentenced to death in 2005 following a spate of deadly hotel bombings in Amman – for al-Kasasba.