Islamist militants have advanced toward Baghdad after seizing control of more territory just 90 kilometers, or 56 miles, north of the Iraqi capital.
In lightning-quick strikes in recent days, fighters from the Sunni Muslim Islamic State of Iraq and the Levant have captured most of the northern reaches of the country. In the latest attack, the militants took the town of Dhuluiyah.
A spokesman for the rebels, who are seeking to install an Islamic government, vowed they would push into Baghdad and on to Karbala, a city southwest of Baghdad that is one of the holiest sites for Shi'ite Muslims.
A spokesman for the rebel group, an offshoot of al-Qaida, vowed they would push on to Baghdad and then Karbala, a city that is home to one of the holiest sites for Shi'ite Muslims.
Al-Jazeera reported the ISIL was marching toward Sammara, home to one of the most venerated Shi'ite places of worship in Iraq.
The militants have seized several other key cities in a blow to Iraq's Shi'ite-led government.
In another development, Iraqi officials said Kurdish forces have taken control of the disputed northern city of Kirkuk. The city is in an area that Kurds want to incorporate into their autonomous region, against the central government's wishes.
"The whole of Kirkuk has fallen into the hands of peshmerga
," said Jabbar Yawar, a spokesman, referring to the Kurdish forces. "No Iraqi army remains in Kirkuk now."
Yawar told Iraqi satellite channels that government soldiers had abandoned 300,000 to 400,000 weapons and a number of planes when they withdrew from Iraq's Mosul, which the militants seized Tuesday.
In Mosul, the ISIL staged a parade of American Humvees seized from the collapsing Iraqi army.
Two helicopters, also seized by the militants, flew overhead, witnesses said, according to a report by Reuters. It apparently was the first time the militant group has obtained aircraft in years of waging insurgency on both sides of the Iraqi-Syrian frontier.
The Iraqi air force bombed insurgent positions in and around the northern city of Mosul on Thursday, footage aired on state television showed.
U.N. Security Council addresses crisis
The U.N. Security Council discussed the situation in Iraq during a session Thursday. Ahead of the meeting, it issued a statement strongly criticizing the ISIL militants for their attack on Mosul, Iraq's second largest city.
Russian envoy Vitaly Churkin, heading the 15-member council for the month of June, said it "strongly condemned all terrorist and extremist acts" and offered its unanimous support for Iraqis in the fight against terrorism. He added that council members also stressed the importance of "inclusive national dialogue" in rebuilding Iraq's government.
The members said "no act of violence or terrorism" can reverse Iraq's path toward peace and democracy.
US considers options
This image from video posted by Iraqi0Revolution, a group supporting ISIL, shows a militant standing in front of a burning Iraqi Army Humvee in Tikrit, Iraq, June 11, 2014.
This image made from video posted by Iraqi0Revolution, a group supporting ISIL, shows militants at the Al-Sharqat base north of Tikrit, Iraq, June 11, 2014.
Kurdish police stand guard while refugees from Mosul head to the self-ruled northern Kurdish region outside Irbil, Iraq, June 11, 2014.
A refugee from Mosul stands outside her family's tent at Khazir refugee camp outside Irbil, Iraq, June 11, 2014.
Iraqi security forces head to Baghdad on the main road between Baghdad and Mosul, a day after fighters from the Islamic State of Iraq and the Levant took control of much of Mosul, Iraq, June 11, 2014.
Iraqi security forces leave a military base as Kurdish forces take over control in Kirkuk, Iraq, June 11, 2014.
A burnt vehicle belonging to Iraqi security forces is seen on a road one day after insurgents seized control of the city of Mosul, June 10, 2014.
Damaged vehicles belonging to Iraqi security forces are seen during clashes between Iraqi security forces and the Islamic State in Iraq and the Levant in Mosul, Iraq, June 10, 2014.
The United States is also weighing how to help Iraq counter the surge by the militants who now control Mosul, Tikrit and Fallujah.
U.S. officials, speaking on condition of anonymity, said one in a range of options under consideration is whether to send drones to Iraq.
White House Deputy Press Secretary Josh Earnest said the U.S. will continue giving Iraq "all appropriate assistance" to fight the al-Qaida offshoot ISIL, but did not give details of specific aid.
State Department spokeswoman Jen Psaki also declined to give specifics, but said the U.S. is working with Iraqi leaders on a coordinated response. She also highlighted expedited shipments of military equipment to Iraq earlier this year, as well as increased training of Iraqi security forces.
Amid rising security concerns, Americans working in Iraq were being temporarily evacuated by their companies Thursday, the State Department told VOA. Fox News had reported that “three planeloads” of Americans, mostly military contractors and civilians, were being cleared from a base in Balad. One of the largest training missions in Iraq, Balad lies 93 kilometers, or 58 miles, northwest of Baghdad.
The State Department has no record of the number of Americans living and working in Iraq, a spokesman said. He added that there has been no change in staffing at the U.S. Embassy and consulates.
Germany's foreign ministry urged its citizens to temporarily leave parts of Iraq, including the capital and the governorates of Anbar, Ninevah and Salah al-Din, the Associated Press reported.
Russia Foreign Minister Sergey Lavrov said Thursday that unrest threatens Iraq's territorial integrity, Reuters reported, citing the Interfax news agency.
"We are concerned about what's happening in Iraq," Lavrov said. "The [territorial] integrity of Iraq is in question."
Maliki urges residents to retake Mosul
Iraq's Prime Minister Nouri al-Maliki and Ninevah Provincial Governor Athil Nujeifi called on residents to fight to retake Mosul.
Maliki blasted Iraqi military officials who deserted their posts and fled Mosul, claiming in a speech Wednesday that they were part of a plot.
Also Thursday, the Iraqi government had been seeking extraordinary powers to deal with militants from the ISIL. But an urgent parliament session to impose a state of emergency was canceled due to a lack of a quorum.
Shi'ite deputy speaker of parliament Khaled al-Attiyah said the government will now seek the approval of Iraq's Federal Court for the state of emergency measures that it needs due to the current crisis.
ISIL said in a statement it was now advancing on Baghdad.
The International Organization for Migration said the fighting there caused 500,000 people to flee their homes.
Iraq is dealing with its worst violence since 2008, with the U.N. saying that about 4,500 people have been killed this year. More than 900 of the deaths came last month.
Some information for this report provided by Reuters.