Iraqi deputies agreed to meet on Sunday after delays to the formation of a new government outraged people tired of political polarisation and fearful of a brutal Sunni militant offensive.

It was unclear what prompted the about-turn after lawmakers initially said they would postpone a crucial parliamentary session for a month, but the delay was met with widespread criticism both from their constituents and internationally.

The month-old crisis has seen a jihadist-led alliance overrun large swathes of northern and north-central Iraq, displacing hundreds of thousands and piling pressure on Nuri al-Maliki as he seeks a third term as prime minister.

With a farcical opening session having ended in disarray last week, and MPs having failed to carry out their constitutional duty to elect a speaker, lawmakers announced they would next meet on August 12, which would have been more than three months after their election.

They later backed down, with the interim speaker scheduling their next meeting for July 13, but the initial decision nevertheless angered ordinary Iraqis.

"The postponement of the parliamentary session was a shock to Iraqis living amid a sea of blood and a lack of services and jobs," said Essam al-Bayati, a professor at the University of Kirkuk.

A Baghdad grocer who gave his name as Abu Mussa said: "We have a crisis, and this postponement for calculations and deals between politicians is the biggest betrayal of the Iraqi people who went out to vote for them."

Though the constitution calls for the speaker, president and premier to be chosen in a sequence over a maximum of 45 days, in practice political leaders normally agree the posts in a package.

In a de facto agreement that has emerged following previous elections, the speaker is a Sunni Arab, the premier a Shiite Arab and the president a Kurd.

Despite telling AFP in 2011 that he would not seek a third term, Maliki vowed last week he would not bow to mounting international and domestic pressure to step aside and allow a broader consensus.

- Iraq forces regrouping -

Iraqi forces have largely regrouped after the debacle that saw soldiers abandon their positions as jihadist-led militants conquered second city Mosul and advanced to within 80 kilometres (50 miles) of Baghdad.

But while Iraq has received support, including equipment, intelligence and advisers from the United States, Russia, Iran and even Shiite militias it once shunned, efforts to battle the militant offensive were dealt a blow when a senior general was killed on Monday.

Staff Major General Najm Abdullah al-Sudani, commander of the army's 6th division, was killed west of Baghdad, near where security forces have been locked in a more than six-month standoff with militants who hold Fallujah.

For more than a week, government forces have also tried to retake the Sunni stronghold of Tikrit from a loose alliance of Islamic State fighters, other jihadists and loyalists of executed dictator Saddam Hussein, but have so far failed to do so.

Air strikes carried out in Salaheddin and Nineveh provinces on Sunday and Monday killed 28 people, many of them said to have been civilians.

The security forces have been hamstrung by a lack of combat experience and a dearth of intelligence in Sunni areas, the result of widespread distrust of the Shiite-led authorities among minority Sunni Arabs, analysts say.

North of Baghdad, a suicide bombing and a roadside bomb targeting security forces killed eight people on Tuesday, six of them police, officials said.

And with government forces still looking for a major victory, the jihadists of the Islamic State appeared to be brimming with confidence.

A few days after declaring the establishment of a "caliphate", the group's leader Abu Bakr al-Baghdadi -- second only to Al-Qaeda chief Ayman al-Zawahiri on the US most wanted list -- delivered a Friday sermon in Mosul's largest mosque.

The group has attracted large numbers of foreign fighters, analysts say, drawn by Baghdadi's own appeal as well as IS's aims of establishing an ideal Islamic state.

Most of the Western foreign fighters who join the group are believed to come from Europe, with US Attorney General Eric Holder estimating Tuesday that fewer than 100 Americans were fighting for the jihadists.