Bombs in Baghdad's mostly Shiite district of Sadr City killed at least 12 people late on Thursday, security officials said, a day after the capital suffered its worst attacks in more than a month.
The latest spike in attacks -- two security force members were also killed in separate incidents -- comes amid discussions between Baghdad and Washington over whether to keep an American training mission in Iraq beyond 2011.
At least two roadside bombs detonated at around 8:30 pm (1730 GMT) in Al-Hay market in the northern Baghdad district, officials from the interior and defence ministries said.
The defence ministry official said two blasts killed 12 people and wounded 18, while the interior ministry official said three bombs exploded, killing 18 people and wounding 43.
Both officials, who spoke on condition of anonymity, said women and children were among the casualties, while the interior ministry official said six policemen and three soldiers were among the wounded.
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The interior ministry official also said gunmen shot dead an intelligence officer at a checkpoint in Al-Amil in south Baghdad, while a roadside bomb against an army patrol killed one soldier and wounded two others just outside Tikrit, in Iraq's north.
Also on Thursday, police arrested more than 300 men allegedly "involved in implementing terrorist and criminal attacks against security forces," according to Major General Fadhel Raddad, police chief of central Babil province, where the arrests were carried out.
Thursday's violence came a day after a spate of attacks in the capital mainly targeting security forces, including two suicide car bombs minutes apart against police stations, killed 23 people and wounded more than 70.
Those apparently coordinated attacks were the deadliest to hit the capital since August 28, when a suicide attack blamed on Al-Qaeda at Baghdad's biggest Sunni mosque killed 28 people, including an MP.
The attacks come with less than three months to go before a year-end withdrawal deadline for the roughly 41,000 US soldiers currently in Iraq, with Baghdad and Washington yet to reach an accord on a post-2011 training mission.
Despite a decline in violence nationwide since its peak in 2006 and 2007, attacks remain common. A total of 185 Iraqis were killed in violence in September, according to official figures.