Six car bombs have exploded across Baghdad, killing at least 34 people and wounding scores more, in what officials say was a co-ordinated attack by al-Qaeda in Iraq fighters.
A blast at a popular market in the Shia neighbourhood of Sadr City in east Baghdad killed at least 10 people and wounded 65 others in Monday's attack.
Another car bomb blew up next to a group of people waiting for work, killing six people and wounding 16 more.
Hours later, south Baghdad's Um al-Maalif neighbourhood was shaken by two blasts in a market, killing 12 and wounding 25 people.
Two other explosions hit a market area of Hussainiya, on Baghdad's northern outskirts, killing four people, and a street in eastern Baghdad, apparently targeting the convoy of an interior ministry official, killing one of his guards and a bystander.
Sahwa arrests
The attacks followed a week of arrests in Baghdad by the Iraqi government of Sunni Arab fighters known as Awakening Councils, or Sahwa.
The Iraqi government insists it is only detaining those wanted for grave crimes, but the fighters - many of them former fighters - fear it is settling sectarian scores.
Kadhum al-Muqdadi, a Baghdad University professor, suggested the bombs might be an attack in response to the raids, one of which sparked clashes just over a week ago between Iraqi forces and supporters of an arrested Sahwa leader.
An Iraqi police officer stands next to a bombed car at the site of an attack in Baghdad [AFP]
"Any security action carries the risk of a reaction," he said.
"These could be the work of Sahwas or just of opportunists exploiting this issue."
The Sahwas first switched sides and joined with US forces to fight al-Qaeda in Iraq in late 2006, manning checkpoints and conducting raids.
US officials have doubted claims that the Awakening Councils may have been behind Monday's bombings.
Lieutenant-Colonel Philip Smith, a military spokesman, said: "Our assessment is that the attacks today were a co-ordinated effort by al-Qaeda. There were no indicators that the [Sahwa fighters] ... were involved in any of the attacks."
Sheikh Hameed al-Hayyes, a founder of the Sahwa movement, also said the bombs were unlikely to be the work of the guards.
"There were bombings in Baghdad before the arrests and after the arrests," he said, blaming al-Qaedain Iraq for the attacks.
Al-Qaeda fingerprints
Qassim al-Moussawi, a Baghdad security spokesman, said the attacks "carry the fingerprints of al-Qaeda-linked groups".