AT LEAST 71 people were killed and 201 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.

It was not immediately clear who carried out yesterday's attacks, which appeared co-ordinated, but Sunni Muslim insurgents including the al Qaeda-affiliated Islamic State of Iraq have significantly 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 Shi'ite Muslim, Sunni Muslim and Kurdish factions.

In Sadr City, an impoverished Shi'ite district in Baghdad's northeast, two car bombs killed seven people. A restaurant owner said he saw an attacker just before one of the explosions.

The businessman said: "A man parked his car in front of the restaurant. He got breakfast and drank his tea. (Then) I heard a huge explosion when I was inside the kitchen.

"When I went outside, I saw his car completely destroyed and he had disappeared. Many people were hurt."

Another car bomb killed seven people and wounded 23 in Jisr Diyala in south-eastern Baghdad.

The Interior Ministry described the attacks as terrorist explosions. The Shi'ite-led Baghdad government says media reports exaggerate attacks in Iraq and that security forces have stopped many attempted bombings.

However, yesterday's violence was the worst since August 10, when nearly 80 people were killed during a religious holiday.

More than 1000 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 stirred anxiety about a relapse towards the widespread sectarian slaughter of 2006/07.

In other attacks yesterday, gunmen killed six members of al Sahwa - former Sunni insurgents who rebelled against al Qaeda - in an ambush on a checkpoint in Latifiya, a suburb 25 miles south of Baghdad.

Gunmen also stormed a Shi'ite home in the same area, killing six family members while in Kadhimiya, a neighbourhood in north-western Baghdad, two roadside bombs and one car bomb killed five people and wounded nearly 30.

Four soldiers also were killed and five were wounded in Madaen, south-east of Baghdad, by a roadside bomb that targeted an Iraqi army patrol.

A few hours after the blasts, Prime Minister Nouri al Maliki said Iraq had put its security forces on high alert ahead of an expected international strike on Syria.

The intensity of attacks has dramatically risen since the start of this year. Bombings often target cafes and other places where families gather, as well as military facilities and checkpoints.