A week-long militant offensive that has overrun swathes of Iraq is "life-threatening" for the country and a danger to the whole region, the UN envoy to Baghdad told AFP.
Nickolay Mladenov's remarks came as militants made gains north of the capital and fighting reached the confessionally-mixed city of Baquba, just 60 kilometres (35 miles) from Baghdad, with security forces struggling to halt the assault.
The crisis has displaced hundreds of thousands of people and sparked fears the violence could affect the country's critical oil production, with militants having declared they will push on towards Baghdad and the southern Shiite holy city of Karbala.
"Right now, it's life-threatening for Iraq but it poses a serious danger to the region," Mladenov said in an interview on Monday.
"Therefore, there needs to be a realisation in the region. The Iraq crisis must be solved by the Iraqis but they cannot do that without the international community and the constructive cooperation of the region."
"Otherwise, it risks becoming a regional crisis."
He added that "Iraq faces the biggest threat to its sovereignty and territorial integrity" in years.
Mladenov, the special representative of the UN secretary general, told AFP the "national crisis" had strained relations between the country's three main communities -- Shiite Arabs, Sunni Arabs and Kurds.
"The political dynamics of the country have changed," he said, speaking in his office.
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- Political action needed -
Militants, led by jihadists from the Islamic State of Iraq and the Levant (ISIL), have taken control of all of one province and parts of three others north of Baghdad in a swift offensive.
Soldiers and police retreated en masse as the insurgents, among them fighters loyal to ISIL and other groups such as supporters of executed dictator Saddam Hussein, swept into Iraq's second city of Mosul a week ago, leaving vehicles and even uniforms in their wake.
Their retreat, despite their numerical advantage, is the result of what experts say are myriad problems, ranging from lacklustre training and low morale, to corruption and an atmosphere of simmering sectarianism.
Violence in Iraq has worsened considerably over the past year, even before the recent offensive, partially attributed by diplomats and analysts to anger in the Sunni Arab community over perceived mistreatment at the hands of the Shiite-led government.
That anger, they say, makes Sunnis less likely to cooperate with the security forces and provide intelligence, helping foster an environment of instability.
Mladenov noted, however, that along with tackling the insurgents on the battlefield, Iraq would have to propose a "strong political package... to be able to address the concerns of people."
He said any long-term solutions would need to be addressed "only through an inclusive democratic process", and warned many Iraqi leaders were "playing politics".
"They need to come together, rather than play the 'blame game'," he said.
The crisis has seen the US weigh the possibility of drone strikes and hold brief talks with long-time foe Iran, Iraq's eastern neighbour, while several countries have responded by evacuating their nationals and downsizing their embassies.