At least a dozen explosions -- most of them car bombs, but also at least one suicide attack -- went off in the Iraqi capital, as well as a confessionally mixed town just to its south, security and medical officials said.

The attacks also wounded about 140 people, the officials added.

They came despite widely publicised security operations targeting militants in the capital and to the north and west, though the government has faced criticism it is not dealing with the root causes of Iraq's worst violence since 2008.

The rise in unrest since the beginning of the year, with more than 3,700 people killed in 2013, has sparked concerns the country is teetering on the edge of a return to the brutal all-out sectarian war that plagued it in 2006 and 2007.

The deadliest attack on Wednesday struck in the Jisr al-Diyala neighbourhood of southeast Baghdad, with at least seven people killed and 21 others wounded in twin bombings.

Another car bomb in the Baghdad Jadidah area, which left four dead, also badly damaged nearby cars and shopfronts, a journalist said.

All that was left of the car bomb was mangled metal, while onlookers railed against the authorities for failing to ensure security.

Blasts also went off in other major Shiite neighbourhoods including Kadhimiyah and Sadr City.

The officials gave varying tolls, which is common in the chaotic aftermath of bombings in Baghdad, and the number of casualties appeared to be increasingly rapidly.

No group immediately claimed responsibility for the attacks.