BAGHDAD (REUTERS) - Prime Minister Nuri al-Maliki vowed to eradicate Al-Qaeda in Iraq and predicted victory as his army prepared to launch a major assault against the Sunni Islamist militants who have taken over parts of the city of Falluja.

Fighters from the Al-Qaeda affiliated Islamic State of Iraq and the Levant (ISIL), which is also active across the border in Syria, overran police stations in Falluja and another city in Iraq's western Anbar province last week.

The campaign by Al-Qaeda gunmen to form a radical Islamic state in parts of Iraq and Syria has rung alarm bells in Western capitals and provided further evidence that the Syrian civil war is exporting instability throughout the region.

In a televised address on Wednesday, Mr Maliki also thanked the international community for its support in the fight against Al-Qaeda and urged the group's members and supporters to surrender, promising clemency.

The prime minister spoke for the second time this week with US Vice President Joe Biden, the White House said in a statement. Mr Biden urged Mr Maliki to keep working with local leaders and welcomed a decision to compensate tribal militiamen who may be wounded or killed in action against ISIL.

The United States said earlier this week it would fast-track deliveries of military hardware, including drones and missiles, to Iraq, but ruled out sending troops two years after Washington ended nearly a decade of occupation. "The support ... is giving us the confidence that we are moving on the right course and that the result will be clear and decisive: uprooting this corrupt organization," Mr Maliki said.

"We will continue this fight because we believe that Al-Qaeda and its allies represent evil." The army deployed more tanks and artillery around Falluja on Tuesday as local leaders tried to persuade militants to leave in order to avert an impending offensive that has echoes of US assaults on the same city in 2004.

The United Nations described the humanitarian situation in Anbar as critical: "The situation in Falluja is particularly concerning, as existing stocks of food, water and life-saving medicines begin to run out," UN envoy to Iraq Nikolay Mladenov said in a statement.

Nevertheless, community leaders in Falluja have asked residents who fled the city to return and go back to work, after forming a local administration and appointing a new police chief and mayor.

In an audio recording released late on Tuesday, ISIL spokesman Abu Mohammad al-Adnani urged Iraq's Sunnis not to lay down their arms or compromise with the Shi'ite-led government.

It is unclear how many fighters ISIL has in Falluja, or how much support it might have from disgruntled tribes in the area, making it hard to predict the course of any attack by Iraqi troops.

In late 2004, more than 10,000 US troops fought weeks of street battles with several thousand insurgents in the city, but ISIL appears to have much smaller forces and many may choose to slip away if faced with a full-on army assault. "We don't want this city to suffer and we will not use force, as long as the tribes announce their readiness to confront Al-Qaeda and expel it," Mr Maliki said.