Iraq’s Shia-dominated government launched air strikes on Sunni insurgent positions in and around the country’s second city of Mosul as Islamist forces hurtled toward the capital and Kurdish troops seized control of the key oil city of Kirkuk.

The latest moves by the country’s major ethnic and sectarian groups raised fears of a deepening of Iraq’s de facto partition into separate Shia, Kurdish and Sunni areas. “The state of Iraq is in imminent collapse,” said Faisal Istrabadi, Iraq’s former deputy ambassador to the UN.

State television aired images of what it described as air strikes on insurgent positions in Mosul, the capital of an oil-rich province, seized on Tuesday by militants from the Islamic State of Iraq and the Levant (known as Isis) as Iraqi forces abandoned their posts.