The attackers detonated a car bomb in the Sunni district of Adhamiyah, then minutes later a suicide bomber ran into the resulting melee and blew up, according to defence and interior ministry officials.

A third explosion caused by a roadside bomb around 30 metres (yards) from the first two blasts tore through the market moments later, according to an Iraqi police officer who was on the street when the attack took place.

An interior ministry official said at least 68 people were wounded in the rush-hour Baghdad attack, which wreaked the heaviest toll in Baghdad since June 17 when 51 people were killed and 75 wounded in a car bombing.

Monday's attack took place on Kassra street, a road lined with restaurants and tea shops popular for breakfast with Iraqi security forces, as a bus carrying young school girls drove past, according to witnesses.

"There was a huge explosion and before I went out to look another bomb went off," said Fadel Hussein, a waiter at a teahouse near the scene.

"Heavy smoke was everywhere. There were so many bloody victims on the ground, we helped to evacuate those people to ambulances," Hussein told AFP.

The US and Iraqi military cordoned off the area, which was littered with glass, mangled metal and scorched cars as sobbing parents desperately searched for their children.

One woman in her 40s and wearing a black abaya, the traditional black Arab dress, sat on the ground crying uncontrollably.

"I'm waiting for my husband who is inside the area looking for my son. I hope he is still alive," she sobbed.

Witnesses told an AFP photographer that some schoolgirls in the bus had died in the blast.

Seats in the wrecked interior of the minibus were heavily stained with blood, while its exterior was riddled with fist-sized shrapnel holes. Girls' shoes lay strewn on the blood-stained street.

Among those killed were three policemen, three women and five children, police said.

The Medical City hospital received 37 wounded people, including several women and children and two Iraqi soldiers, a medic said.

However, the US military put the toll at four killed and 34 wounded.

Meanwhile in Baquba, a restive city north of Baghdad, a female suicide bomber killed four Sunni guards belonging to Awakening councils and wounded at least 15 civilians at a checkpoint.

A doctor who examined the remains of the attacker said she was likely a 13-year-old girl.

The United Nations envoy to Iraq, Staffan de Mistura, condemned the attacks that "aimed at re-instilling fear, distrust and division among the public just as Iraq prepares itself to assume political normalcy with the upcoming provincial elections."

On Sunday, Baghdad set January 31 as the date for long-awaited provincial elections seen by Washington as a key benchmark towards national reconciliation but also capable of stoking further conflict among Iraq's divided communities.

The bombings also came as Sunni militias which have played a key role in driving Al-Qaeda fighters from Baghdad began receiving pay cheques from a Shiite-led government that has long eyed them with suspicion.

Up to 60 stations opened throughout the Iraqi capital to pay some 50,000 members of the US-allied Awakening Councils or Sahwas which used to receive their monthly salaries from the American military.

Despite the dramatic improvement in security in large swathes of Iraq, militants continue to launch near daily attacks , most of them targeting US and Iraqi security forces.

Baghdad has been hit by a string of bombings in the last week, most of them small roadside bombs that claimed only a handful of victims.

The US military says the capital has become much safer since the launch last year of a joint Iraqi-US security plan. Attacks average four a day, 83 percent less than in 2007. >>>> 

Triple bombings just latest in uptick of violence in Iraq