As many as 500,000 people have been forced to flee Iraq’s second city of Mosul after Islamist militants effectively took control of it.
Troops were among those fleeing as hundreds of jihadists from the ISIS group overran the city and much of the surrounding province of Nineveh.
Iraqi PM Nouri Maliki responded by asking parliament to declare a state of emergency to grant him greater powers.
The US said the development showed ISIS is a threat to the entire region.
ISIS – the Islamic State of Iraq and the Levant – is an offshoot of al-Qaeda which now controls considerable territory in eastern Syria and western and central Iraq, in a campaign to set up a militant enclave straddling the border.
Residents of Mosul said jihadist flags were flying from buildings and that the militants had announced over loudspeakers they had “come to liberate” the city.
“The situation is chaotic inside the city, and there is nobody to help us,” said government worker Umm Karam. “We are afraid.”
Many police stations were reported to have been set on fire and hundreds of detainees set free.
“The army forces threw away their weapons, changed their clothes, abandoned their vehicles and left the city,” Mahmud Nuri, a resident fleeing Mosul, told the AFP news agency.
Meanwhile, the Turkish consulate in Mosul confirmed reports that 28 Turkish lorry drivers had been abducted by militants in Nineveh province.
US State department spokeswoman Jen Psaki said the situation in Mosul was “extremely serious” and that the US supported “a strong, co-ordinated response to push back against this aggression”.
A spokesman for UN Secretary-General Ban Ki-moon said he was “gravely concerned” at the situation.