A string of powerful bomb attacks targeting Shiite Muslim worshippers as they emerged from mosques across Baghdad on Friday killed 28 people and wounded 63, security officials said.
The six apparently coordinated blasts occurred outside mosques and prayer centres in and around the Iraqi capital, including one frequented by followers of radical Shiite cleric Moqtada al-Sadr, they said.
The most devastating attack was in the northeastern Baghdad district of Al-Shaab, where a car bombing killed 21 people and injured 35 others, an interior ministry official said.
"At least 21 people were killed and 35 wounded by a bomb targeting citizens while they were leaving Al-Shurufi mosque in Al-Shaab," a security official said on condition of anonymity.
The mosque itself is occupied by the Iraqi military, and before the car bomb exploded worshippers, many of them loyal to Sadr, were praying between the building itself and the parking lot.
Witnesses at the mosque said the 1980s Volkswagen Passat had raised suspicions, with worshippers trying to alert police when the bomb exploded.
In the aftermath, police cordoned off the area but faced verbal abuse from local residents, who said they blamed Iraqi security forces for not doing their job.
Meanwhile, in twin bombings at Diyala bridge, 10 kilometres (six miles) south of Baghdad, five people were killed and 15 wounded, an interior ministry official said.
Attacks in Zafaraniyah and Kamaliyah neighbourhoods killed one person each and left six and three people wounded respectively. A separate attack in Al-Elam in western Baghdad injured four.
Attacks in the capital over the past two months have mostly targeted Iraq's majority Shiite community, prompting fears of efforts by Al-Qaeda to reignite the sectarian violence that swept the country in 2006 and 2007, killing tens of thousands of people.
Violence has dropped markedly throughout Iraq in recent months, but attacks increased in the run-up to the US military pullback a month ago from urban centres, with 437 Iraqis killed in June -- the highest death toll in 11 months.
Attacks remain particularly common in Baghdad and the restive northern city of Mosul.
Violence has claimed several lives over the past week.
On Thursday 11 people were killed in two separate attacks, one against a political party's offices in Baquba, north of Baghdad, while the other targeted a police station near the Iraq-Syria border.
On Wednesday a senior US commander warned that security forces would have to be watchful of violence targeting parties and politicians in the run-up to general elections next January.
"Leading up to the elections, we're also going to see some politically motivated violence," said Colonel Tobin Green, commander of the US army's 1st Brigade, 1st Cavalry Division.
On Tuesday, 10 people were killed and 42 others were wounded in a string of attacks in Baghdad,
including a motorcycle bomb near a cinema in a crowded area of the predominantly Shiite neighbourhood of Baghdad Jadida.
Those bombings came as US Defence Secretary Robert Gates visited Iraq to assess the security situation after American troops withdrew from urban centres at the end of June.
On Monday, a senior Iraqi army officer, a Sunni tribal chief and two Iraqi special forces soldiers were among six people killed in violence across the country.