Sunni militia
Iraq launches attack to retake Tikrit from Islamic State
Iraq's armed forces, backed by Shi'ite militia, attacked Islamic State strongholds north of Baghdad on Monday.
Bombings across Iraq kill 35 in attacks that appeared to be revenge for an assault on a Sunni mosque.
Barack Obama authorised the first US air strikes on Iraq since he pulled all troops out in 2011.
The army said it now held the 50 km stretch of main highway running north from the city of Samarra.
Armoured vehicles were sent to try dislodge insurgents from the northern city of Tikrit.
Sunni fighters seized a border post on the Iraq-Syria frontier, smashing a line drawn by colonisation.
Baghdad said it wanted US air strikes on insurgents led by fighters from the Islamic State of Iraq.
Nuri al-Maliki has appealed to bitter Sunni critics for national unity.
No group has yet claimed responsibility for the seven attacks.
It was not immediately clear who was behind the attack.
Sunni Muslim worshippers were leaving the mosque following Friday prayers in the Iraqi city of Baquba.