On Wednesday evening, car bombs in a mainly Shia district of the city killed 18 people, after a day of talks in Brussels between the new Shia-led government, its US backers and other nations.
Despite a month-long crackdown by US and Iraqi troops and police in Baghdad, al-Qaida allies and other groups have mounted major attacks on three days this week, while lower-level violence is keeping up pressure on all security forces.
Police said a car bomber killed three police officers and seven civilians when he drove at their patrol in the central commercial district of Karrada about 7am (0300 GMT). A second, similar attack killed seven civilians, they said.
Two other cars exploded in the same area, several minutes apart, one near a Shia mosque. Police and medical sources put the number of wounded at 23 to 50.
The Army of Ansar al-Sunna said in an internet statement it had carried out the three bombings in a joint operation with the Islamic Army in Iraq and the Mujahidin Army.
It said it had exploded a car bomb at a convoy of Iraqi police and when other police vehicles gathered around the blast site, "they entered into the mujahidin ambush where two other cars were detonated". The group later said it exploded a fourth car against Iraqi police in the same area, killing seven.
Shelling of a house in a Baghdad
suburb killed suspected fighters
About 1200 people, including around 120 US troops, have been killed in political violence since the Shia-led government was formed two months ago.
In addition to the 18 dead, Wednesday night's coordinated bomb attacks wounded 48 in the Shia Shola district of Baghdad, police said. The area's main street was devastated.
The al-Qaida organisation in Iraq, led by Jordanian Abu Musab al-Zarqawi, claimed responsibility for Wednesday's "Sunni reprisal raid".
Abu Musab al-Zarqawi's group
said US forces killed five fighters
Al-Zarqawi's group said an Iraqi and four foreign fighters were killed by US forces at a house in Baghdad's Jamiaa area, where residents heard a fierce battle overnight.
Iraq's security minister said he was in touch through intermediaries with some anti-American, nationalist fighters and was trying to break their links to the foreign Islamists.
"There are nationalists within the insurgency who are against the (US) occupation. We are urging them to show their faces and come to the table," Abdul Karim al-Enzi told Reuters.
One of the highest legal authorities in Sunni Islam, the Egyptian Grand Mufti Ali Gumaa, said resisting occupation was a religious duty - but not killing civilians at random.
US Defence Secretary Donald
Rumsfeld rejected a timetable
"Bloody acts which kill civilians under the slogan of jihad to liberate Iraq are a kind of mockery," he said after meeting an Iraqi Sunni cleric.
Meanwhile, in Washington, US Defence Secretary Donald Rumsfeld rejected an assertion by Democratic Senator Edward Kennedy that the Iraq war had become a quagmire, but warned Iraq's government not to delay political developments such as drafting a constitution or elections under the new constitution.
"Any who say that we've lost this war or that we're losing this war are wrong," he said at a tense Senate hearing on Thursday.
Rumsfeld opposed a call in the Senate to consider setting a timetable for a withdrawal of US forces from Iraq, saying it would "throw a lifeline to terrorists".
But statements by US officials that the insurgency is fading have been met with scepticism from some lawmakers who are questioning President George Bush's Iraq policy two years into a conflict in which 1725 US soldiers have died.
Army General John Abizaid, who as head of Central Command is the top US commander in the Middle East, declined to endorse Vice-President Dick Cheney's assessment that the armed opposition in Iraq was in its "last throes". He said more foreign fighters were coming into Iraq than six months ago.
"There's a lot of work to be done against the insurgency," Abizaid said.