Dozens of attacks across Iraq on Monday, including a brazen car bombing en route to Baghdad airport, killed at least 24 people just days before the country's first elections since US troops withdrew.
The violence, which struck during morning rush hour amid tightened security ahead of the polls, also wounded more than 210 people and raises further questions about the credibility of the April 20 vote, seen as a key test of Iraq's stability and its security forces' capabilities.
A total of 14 election hopefuls have already been murdered and just 12 of the country's 18 provinces will be taking part.
Officials said 20 car bombs exploded Monday in Baghdad, the northern cities of Kirkuk, Tuz Khurmatu, Mosul and Tikrit, the central city of Samarra, and Hilla and Nasiriyah south of Baghdad.
Roadside bombs also hit Baquba, north of the capital, and there was a shooting near Baghdad.
No group immediately claimed responsibility for the attacks, but Sunni militants linked to Al-Qaeda frequently attack both government targets and civilians in a bid to destabilise the country, and have reportedly sought to intimidate candidates and election officials ahead of polls.
The deadliest attacks were in Baghdad, where six car bombs struck in five neighbourhoods across the capital despite tougher checkpoint searches and heightened security.
Among them was a car bomb in a parking area used by vehicles making their way to Baghdad's heavily-guarded airport, a rare bombing on the road famously known as "Route Irish".
The airport road was once known by American forces as "RPG alley" for the high numbers of attacks along it but has since become much more secure.
"There were several people, buses and private cars in the parking area when the explosion went off," said a man who gave his name as Abu Ali, at the site of the blast.
"It happened all of the sudden, and several people were killed and wounded. Some of the buses went straight to the airport to avoid more attacks."
In all, 11 people were killed and 57 wounded in the capital, officials said.
AFP journalists in Baghdad reported that sites of attacks were cordoned off by security forces who barred reporters from filming or taking photos of the aftermath of the bombings.
In Tuz Khurmatu, which lies 175 kilometres (110 miles) north of Baghdad, six people were killed and 60 wounded by three near-simultaneous car bombs, and in Kirkuk, five people were killed and 26 wounded by four more car bombs.
Attacks elsewhere in Iraq killed one person and wounded 69 others.
Kirkuk and Tuz Khurmatu lie at the centre of a tract of disputed territory that stretches from Iraq's eastern border with Iran to its western frontier with Syria.
The swathe of land is claimed by both the mostly-Arab government in Baghdad and the three-province autonomous Kurdistan region of north Iraq.
The dispute is often cited by officials and diplomats as the biggest long-term threat to Iraq's stability.
Soldiers and policemen cast their ballots for the provincial elections on Saturday, a week ahead of the main vote, the country's first since March 2010 parliamentary polls. It is also the first election since US troops withdrew from Iraq in December 2011.
The election also comes amid a long-running crisis between Prime Minister Nuri al-Maliki and several of his erstwhile government partners, which officials and diplomats say insurgent groups exploit by using the political differences to enhance their room for manoeuvre on the ground.
More than 8,000 candidates are standing in the elections, with 378 seats on provincial councils up for grabs. An estimated 16.2 million Iraqis are eligible to vote.
Although security has markedly improved since the height of Iraq's confessional conflict in 2006-2007, 271 people were killed in March, making it the deadliest month since August, according to AFP figures.