At least 29 people have been killed and dozens wounded in a series of bomb attacks in mostly Shia areas of the Iraqi capital, Baghdad, officials say.

The deadliest attack was in the central Sadriya district, where a car bomb was detonated at an crowded market.

Bombs exploded at around the same time on busy streets in the Shaab, Tobchi, Karrada, Azamiya and Amil areas.

Sectarian violence has surged across the country in recent months, reaching its highest level since 2008.

The UN says 979 people – including 158 police and 127 military personnel – were killed in violent attacks in October. More than 6,500 civilians have died since January.

The Iraqi government has blamed extremist Sunni militants linked to al-Qaeda for the violence, which has mainly targeted Shia civilians.

Earlier this month, Prime Minister Nouri Maliki asked US President Barack Obama for help curbing the bloodshed through greater intelligence sharing and new weapons systems.

But diplomats say Mr Maliki has not done enough to address the causes of the unrest, which was sparked by an army raid on a Sunni Arab anti-government protest camp in April.

The protesters had called for the resignation of Mr Maliki, a Shia, and accused the authorities of targeting the minority Sunni community.

Iraq has also seen a spill-over of violence from the conflict in Syria, where jihadist rebels linked to the Islamic State of Iraq, a Sunni militant umbrella group that includes al-Qaeda, have risen to prominence.

Officials fear militants will try to further destabilise Iraq before the parliamentary elections on 30 April, when Mr Maliki will seek a third term.