Baghdad - A wave of attacks and explosions in Iraq killed 50 people on Tuesday and officials delayed provincial polls, highlighting security concerns on the eve of the 10th anniversary of the US-led invasion.
At least 20 explosions and two assassinations also left more than 170 people wounded in the country's bloodiest day in more than six months, reflecting the brutal unrest and endless political crises that were sparked by an invasion that had aimed to build a democratic ally in the heart of the Middle East.
The attacks come amid a spike in violence that has raised fresh questions about the capabilities of the Iraqi security forces, with separate reports by Britain-based Iraq Body Count and researchers in The Lancet putting the overall death toll from the decade of bloodshed at over 112 000 civilians.
Most of Tuesday's attacks struck in Shi'ite neighbourhoods in Baghdad during morning rush hour, with security forces stepping up searches at checkpoints and closing off key roads, worsening the capital's gridlock, an AFP reporter said.
Soldiers and police also established new checkpoints, and unusually, were searching at least some government-marked vehicles that are typically allowed to pass uninspected.
In all, at least 15 car bombs were set off, including two by suicide attackers, along with multiple roadside bombs and gun attacks, officials said.
No claim of responsibility
Tuesday was the deadliest day since 9 September, when 76 people were killed.
No group immediately claimed responsibility for the violence, but Sunni militants often target Shi'ite civilians and government employees in a bid to destabilise the country.
Violence has spiked ahead of the 10th anniversary, with 114 people killed in the past week, according to an AFP tally based on reports from security and medical officials.
Authorities later announced that provincial polls scheduled for 20 April, which would have been Iraq's first vote in three years, were delayed in two provinces, Anbar and Nineveh, citing security concerns including threats to the lives of candidates.
Iraqi officials have not announced any ceremonies to mark the anniversary on Wednesday, with events more likely to be held on 9 April, the day Baghdad fell.
Launched with the stated goal of wiping out Saddam's stores of weapons of mass destruction, which were never found, the focus of the divisive war quickly shifted to solidifying Iraq as a Western ally in an unstable region.
High levels of violence
Though the war itself was relatively brief - it began on 20 March 2003, Baghdad fell weeks later, and then-US president George W Bush infamously declared the mission accomplished on 1 May - its aftermath was violent and bloody.
Britain-based Iraq Body Count has said that more than 112 000 civilians have been killed since the 2003 invasion, while a study published in The Lancet put the figure at 116 000 from 2003 up to December 2011, when US forces pulled out.
Violence, which remains high by international standards, was only brought under some measure of control from 2008 onwards, as the American troop "surge" coincided with Sunni tribal militias deciding to side with US forces.
But political reconciliation, the strategic goal of the surge, was never fully achieved.
From territorial disputes in the north to questions over the apportioning of the country's vast energy revenues, a number of high-level problems remain unresolved, while Iraqis still grapple with daily struggles ranging from poor provision of basic services to high levels of unemployment.
Prime Minister Nouri al-Maliki's erstwhile government partners, meanwhile, have charged him with monopolising power, and little in the way of landmark legislation has been passed in recent years.
Through it all, however, a bright spot has been Iraq's booming oil sector, which has boosted the government's coffers and is projected to expand still further.
Since the American withdrawal, Iraq's military and police are consistently described by Iraqi and American officials as capable of maintaining internal security, but not yet fully able to protect the country's borders, airspace and maritime territory.