Iraq's Prime Minister Nouri Maliki has rejected calls for a national salvation government to help counter the offensive by jihadist-led Sunni rebels.

Such calls represented a "coup against the constitution and an attempt to end the democratic experience", he warned.

The US has led appeals to the country's political leaders to rise above sectarian and ethnic divisions.

Government forces have been unable to recapture the territory seized by the rebels this month.

Almost half of the 300 US military advisers assigned to help the Iraqi security forces have arrived.

Fighting was reported to have continued on Wednesday, with an attack by rebels on the Balad airbase, about 80km (50 miles) north of Baghdad.

Also on Wednesday, a suicide bombing outside the main market in the northern city of Kirkuk left at least two people dead and many more injured.

The city was seized by Kurdish peshmerga fighters on 12 June when the Iraqi army fled in the face of the rebel advance.

At least nine people were also killed in attacks in the town of Mahmudiyah to the south of Baghdad.