BAGHDAD: Violence in Iraq, including shelling in a militant-held city and an attack targeting Shia pilgrims, has killed more than 30 people in 24 hours, officials said on Sunday.

The bloodshed comes as officials count ballots from the April 30 general election, the first since US troops withdrew in late 2011, and amid a protracted surge in nationwide unrest that has sparked fears of a return to the sectarian killing sprees of 2006-2007.

While officials are quick to blame external factors like the civil war in neighbouring Syria for the heightened violence, analysts and diplomats say widespread anger among the Sunni Arab minority is also a key cause.

In Fallujah, just a short drive west of Baghdad, shelling in southern areas of the city killed 11 people and wounded four, Doctor Ahmed Shami said.

It was not immediately clear who was behind the bombardment, which began on Saturday evening and continued into Sunday.

In a sign of both the reach of anti-government militants and the weakness of security forces, all of Fallujah and shifting parts of Anbar provincial capital Ramadi, farther west, have been out of government control since early January.

The crisis in the desert province of Anbar, which shares a long border with conflict-hit Syria, erupted in late December when security forces dismantled Iraq’s main Sunni Arab anti-government protest camp just outside Ramadi.

Militants subsequently seized parts of Ramadi and all of Fallujah, the first time anti-government forces have exercised such open control in major cities since the peak of the deadly violence that followed the US-led invasion of 2003.

North of Baghdad, a bombing and shooting targeted a bus carrying pilgrims on Saturday evening, killing 11 people and wounded 21, police and a doctor said.

The pilgrims were returning from Samarra when a roadside bomb exploded on the outskirts of the town of Balad and gunmen opened fire on the bus.

Also on Saturday evening, police found the bodies of eight family members shot dead inside their home in a predominantly Sunni area southeast of Baghdad.