In pictures: Inside Iraq cities under attack
Islamist forces are reported to have taken control of the Iraqi city of Tikrit just days after they seized Mosul.
Images taken by eyewitnesses showed smoke rising over the city as jihadist militants continued their advance into different regions of Iraq.
Fighters for ISIS - the Islamic State of Iraq and the Levant - seized the northern city of Mosul on Monday after police and soldiers abandoned their posts.
As many as half a million people have been forced to flee the city, which was left badly battered and strewn with burned-out vehicles.
The streets of Mosul - Iraq's second city - were deserted on Wednesday. ISIS fighters took staff working at the Turkish consulate in the city hostage.
Armed groups were pictured inside Tikrit. It is the birthplace of Saddam Hussein and has been a hotbed of Sunni opposition to the Shia Prime Minister, Nouri Maliki.