At least 27 people were killed in a series of bombings across Baghdad today, including three over a span of less than 10 minutes.
The blasts shook the fragile sense of security the capital has maintained despite the Sunni militant offensive raging across northern and western Iraq.
The attacks are among the most significant in Baghdad since insurgents led by the Islamic State extremist group captured Iraq's second-largest city Mosul last month at the start of its blitz across Iraq.
After Mosul's fall, the government moved aggressively to try to secure Baghdad amid fears it might fall as well, and the city has seen few major attacks in recent weeks.
Today's deadliest bombing took place in the Shiite neighbourhood of Abu Dashir, where a suicide attacker rammed a car packed with explosives into a checkpoint, killing at least nine people and injuring 19, officials said. Four policemen were among the dead, a police officer said.
Later in the day, three car bombs in different areas of Baghdad went off in less than 10 minutes, hitting the districts of Baiyaa, Jihad and Khazimiyah. The attacks killed at least 15 people and wounded another 42, police officials said.
Another car bomb near a bus stop in Khazimiyah killed three people and wounded 15, police said.
Hospital officials in Baghdad confirmed the casualty figures in all of the attacks.
The Sunni militant blitz, led by the Islamic State extremist group, has pushed into areas west of Baghdad, and also has established a presence in a belt of Sunni areas running south and north of the capital. Baghdad itself has a predominantly Shiite population.
The Iraqi military launched a counter-offensive late last month to try to dislodge insurgents from the city of Tikrit, some 80 miles (130km) north of Baghdad. That effort has secured much of the highway between Tikrit and the city of Samarra, home to one of the most important Shiite shrines, but Tikrit itself remains in militant hands.
North-west of Tikrit, heavy fighting has raged around an air base which previously served as a US military facility known as Camp Speicher.
Today, Iraqi military spokesman Lieutenant General Qassim al-Moussawi denied reports that militants had captured Camp Speicher, saying government troops repelled an attack yesterday and the base remains fully in government hands.
Three security officials confirmed that the militants launched an assault on the air field late on Thursday, blasting through an outside wall of the base and destroying one helicopter. One of the officials said the other helicopters at Speicher were "evacuated" from the base to prevent them from being damaged, but they have since been returned to duty.
A resident of Tikrit, Ahmed Jassim, said by telephone that clashes were taking place around Speicher today, but "the gunmen are outside the camp".
The centre of Tikrit is still under insurgent control, and is being shelled by the Iraqi military.
Meanwhile in the northern city of Sulaimaniyah, in the largely autonomous Kurdish region, Iraq's ailing president returned to the country after more than 18 months abroad for medical treatment following a stroke, state TV said.
Jalal Talabani is wrapping up his second consecutive term as president, and is not eligible to run again.
Mr Talabani, who is Kurdish, suffered a stroke in late 2012, and was flown to Germany shortly afterwards for treatment and rehabilitation.
With his term set to expire, Iraqi political leaders are in talks to replace him as part of broader negotiations over forming a new government. Parliament is expected to meet on Wednesday to discuss presidential candidates.
The Iraqi presidency is a largely ceremonial role, with the prime minister acting as the head of government, but Mr Talabani has at times played an important role in mediating disputes among Iraq's ethnic and sectarian factions.