Fighters from the Islamic State of Iraq and the Levant have vowed to march on Baghdad, as Iraq's parliament failed to agree the declaration of a nationwide state of emergency.

"We will march toward Baghdad because we have an account to settle there," said the armed group's spokesman on Thursday in an audio recording posted on the internet. The statement could not be independently verified.

In a sign of ISIL's confidence, he even boasted that its fighters would take the southern Shia cities of Karbala and Najaf, which hold two of the holiest shrines for Shia Muslims, following the fall of cities in the Sunni north.

Its boasts come as Iraq's parliament failed to reach a quorum on Thursday to vote on a nationwide state of emergency.

Most of those boycotting parliament were from the country's Sunni and Kurdish factions, who oppose giving extraordinary powers to the Shia prime minister, Nouri al-Maliki.

"It was a political move. Those parliamentarians that didn't turn up made sure that this state of emergency wasn't declared," said Al Jazeera's Imran Khan, reporting from Baghdad.

"It was hugely criticised by Sunni politicians, saying that Maliki has enough powers to be able to deal with this if only he reached out to the Sunnis and to the Kurds and to the other minorities in Iraq."

The schism came even after days of advances had left ISIL in control of towns 50km from the capital.

On Wednesday, the group seized Tikrit, 140km northwest of Baghdad, as Iraqi soldiers fled.

The day before, it captured Mosul, Iraq's second-largest city. ISIL and its allies among local tribesmen also hold the city of Fallujah and other pockets of the Sunni-dominated Anbar province to the west of Baghdad.

The rise of ISIL in Iraq has caused shockwaves across the region, with Syria saying on Wednesday it and Iraq faced a common enemy,

Hassan Rouhani, the president of Iran, said on Thursday that the predominantly Shia Muslim country would act to combat the "violence and terrorism" of ISIL.

Not every ISIL advance has been successful, however. On Thursday, Iraqi Kurds took control of the disputed Iraqi oil hub of Kirkuk to protect it from ISIL, officials said.

"We tightened our control of Kirkuk city and are awaiting orders to move toward the areas that are controlled by ISIL," said Shirko Rauf, a brigadier general in the Kurdish peshmerga force.