At least 86 people were killed and 263 wounded in a series of bombings and other attacks across Baghdad, extending the worst wave of sectarian bloodshed in Iraq for at least five years.

Car bombs hit south, north and western Baghdad in a cluster of attacks early in the day and late in the evening, which targeted both Shia and Sunni areas of the capital.

It is not yet clear who carried out the attacks, but Sunni Muslim insurgents including the al-Qaeda-affiliated Islamic State of Iraq have stepped up bombings this year.

More than two years of civil war in neighbouring Syria have aggravated deep-rooted sectarian divisions in Iraq, fraying the country's uneasy coalition of Shia Muslim, Sunni Muslim and Kurdish factions.

The Interior Ministry described the attacks as "terrorist explosions", but said the number of people killed was only 20, with 213 wounded.

The latest wave of attacks comes after more than 1,000 Iraqis were killed in July, the highest monthly death toll since 2008, according to the United Nations.

The renewed violence, 18 months after US troops withdrew from Iraq, has also stirred anxiety about a relapse towards the widespread sectarian slaughter of 2006-07.