The rebels occupied several key cities last week
By jadelung, 03:54Her remarks came as the militants, led by the Islamic State in Iraq and the Levant (ISIS), were reported to have seized the strategic city of Tal Afar.
The rebels occupied several key cities last week, but some towns were retaken.
Security in Baghdad has been stepped up after the insurgents threatened to march on the capital.
Reports are emerging that an army helicopter has been shot down in fierce clashes near the city of Fallujah, located just 70km (45 miles) west of Baghdad.
President Barack Obama says the United States is deploying up to 275 military personnel to Iraq to protect American interests there.
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Analysis: Jim Muir, BBC News, Irbil
ISIS militants in Nineveh province (11 June 2014) Iran said it was ready to assist Iraq in its battle against ISIS insurgents, seen here in Nineveh
One reason Tal Afar was important for the government to hold was that the city was the state's only outpost in the entire province of Nineveh, which fell to the Sunni militants last week as the army collapsed.
It is also strategically significant, straddling the main highway from Mosul, the provincial capital, to the Syrian border.
However, assuming Tal Afar has indeed fallen to the militants, it does not mean they have a direct link to Syria - the border crossing at Rabia is controlled on the eastern side by Iraqi Kurdish Peshmerga fighters, and on the western side by the Popular Protection Units (YPG), the armed wing of the Syrian Kurdish Democratic Union Party (PYD), which is fiercely hostile to ISIS.
Tal Afar is important for other reasons too. Most of the areas through which the Sunni militants swept last week were largely Sunni populated. Tal Afar has a big Shia community, from the Turkmen minority, perhaps one reason why it held out longer than any other town in Nineveh.
Some observers believe it is important for Iran - which sees itself as the custodian of the Shia - that Tal Afar should not be allowed to fall, and that they would sooner or later wreak revenge, especially if abuses were committed during or after its capture.