A series of blasts in Baghdad have killed at least 23 people and injured dozens more in a co-ordinated attack designed to wreak havoc across the Iraqi capital.

The blasts were the worst violence to hit the country since a political crisis between Iraq's Sunni and Shiite factions erupted last weekend.

The political spat, which pits Iraq's Shiite prime minister against the highest-ranking Sunni political leader, has raised fears that Iraq's sectarian wounds will be reopened.

Iraqi officials said at least 12 explosions took place early on Thursday morning in nine neighborhoods around the city. The attacks ranged from sticky bombs attached to cars to roadside bombs and vehicles packed with explosives.

Most of the violence appeared to hit Shiite neighborhoods although some Sunni areas were also targeted.

The worst attack was in the al-Amal district, where seven people were killed in a blast that appeared to target rescuers and officials who came to the scene after a previous explosion. At least four people were killed in the west of the city when two roadside bombs exploded.

In the south-west neighbourhood of Karrada, where one of the victims was killed, sirens could be heard as ambulances rushed to the scene and a plume of smoke rose over the area.

"My baby was sleeping in her bed. Shards of glass have fallen on our heads. Her father hugged her and carried her. She is now scared in the next room," said one woman who identified herself as Um Hanin.

"All countries are stable. Why don't we have security and stability?"

While Baghdad and Iraq have become much safer over the years, explosions such as Thursday's are still commonplace and come at a precarious time in Iraq's political history.

The government of the prime minister, Nouri al-Maliki, has accused the Sunni vice-president, Tariq al-Hashemi, of running a hit squad that targeted government officials. Al-Maliki is also pushing for a vote of no-confidence against another Sunni politician, the deputy prime minister, Saleh al-Mutlaq.

Many Sunnis fear this is part of a wider campaign to go after Sunni political figures in general and shore up Shiite control across the country at a critical time when all US troops have left Iraq.

There was no immediate claim of responsibility for the violence. But the co-ordinated nature of the blasts and the fact that the attacks took place in numerous neighbourhoods suggested a planning capability only available to al-Qaida in Iraq.

The Sunni militant organisation is severely debilitated from its previous strength in the early years of the war, but is still able to launch deadly assaults from time to time.

US military officials have said they are worried about a resurgence of al-Qaida after American troops leave the country. If that happens, it could lead Shiite militants to fight back and attack Sunni targets, sending Iraq back to the sectarian violence it experienced a few years ago.