Militants attacked one of Iraq's largest air bases and seized control of several small oilfields on Wednesday, June 25 as U.S. special forces troops and intelligence analysts arrived to help Iraqi security forces counter a mounting Sunni insurgency, according to Reuters.

Iraqi Prime Minister Nuri al-Maliki, who is fighting for his job and is under international pressure to create a more inclusive government, said he supported starting the process of forming a new cabinet within a week.

He also dismissed the call of mainly Sunni political and religious figures, some with links to armed groups fighting Maliki, for a "national salvation government" that would choose figures to lead the country and, in effect, bypass the election held nearly three months ago.

In northern Iraq, the Sunni militants extended a two-week advance that has been led by the hardline Islamic State in Iraq and the Levant (ISIL) but also includes an amalgam of other Sunni groups angered by Maliki's rule.

They blame Maliki for marginalizing their sect during eight years in power. The fighting threatens to rupture the country two and a half years after the end of U.S. occupation.

U.S. Secretary of State John Kerry during a visit this week pressed Iraqi officials to form an "inclusive" government and urged leaders of the autonomous Kurdish region to stand with Baghdad against the onslaught.

A session of parliament is planned within a week that will start the process of forming a new government based on the results of elections held in April. Maliki's Shi'ite-led State of Law coalition won the most seats but needs the support of other Shi'ite groups, Sunnis and Kurds to build a government.

"We will attend the first session of parliament," Maliki said on state television, adding the commitment stemmed from "loyalty to our people" and respect for a call by Iraq's foremost Shi'ite clergy.

On Friday, Shi'ite Grand Ayatollah Ali al-Sistani, the most respected cleric among Iraq's Shi'ite majority, called for the government formation process to begin.

He also warned the demands by mainly Sunni politicians and figures, with ties to the non-ISIL fighting groups who belong to the armed revolt against Baghdad, that calling for an emergency government, not based on the vote, "represents a coup against the constitution."

The fighting waged by armed Sunni groups, with ISIL blazing the path, has knocked towns and cities across the north and west from the central government's control. Northern Iraq's largest city Mosul fell to Sunni insurgents on June 10.

Two days later, Kurdish forces moved into Kirkuk, where violence also flared on Wednesday when a suicide bomber blew himself up at a crowded market entrance, killing six people and wounding 23, police and medics said.

The United Nations says more than 1,000 people, mainly civilians, have been killed during the Sunni insurgents' advance in Iraq, spearheaded by al Qaeda offshoot ISIL.

The figure includes unarmed government troops machine-gunned in mass graves by insurgents, as well as several reported incidents of prisoners killed in their cells by retreating government forces.

In addition to the bloodshed, close to a million people have been displaced in Iraq this year. Amin Awad, director of Middle East and North Africa bureau for the U.N. refugee agency, on Wednesday called Iraq "a land of displacement".