BAGHDAD - A dozen car bombs and suicide blasts tore into Shi'ite Muslim districts across Baghdad and south of the Iraqi capital on Tuesday, killing more than 50 people on the 10th anniversary of the U.S.-led invasion that ousted Saddam Hussein.
Sunni Islamist insurgents linked to al Qaeda are regaining ground in Iraq, invigorated by the war next door in Syria and have stepped up attacks on Shi'ite targets in an attempt to provoke a wider sectarian confrontation.
One car bomb exploded in a busy Baghdad market, three detonated in the Shi'ite district of Sadr City and another near the entrance of the heavily fortified Green Zone that sent a plume of dark smoke into the air alongside the River Tigris.
A suicide bomber in a truck attacked a police base in a Shi'ite town south of the capital, officials said.
"I was driving my taxi and suddenly I felt my car rocked. Smoke was all around. I saw two bodies on the ground. People were running and shouting everywhere," said Ali Radi, a taxi driver caught in one of the blasts in Baghdad's Sadr City.
A decade after U.S. and Western troops swept Saddam from power, Iraq still struggles with insurgents, sectarian friction and political feuds among Shi'ite, Sunni and Kurdish factions who share power in the government.
In a sign of concern over security, the cabinet on Tuesday postponed local elections in two provinces, Anbar and Nineveh, for up to six months because of threats to electoral workers and violence there, according to Maliki's media adviser Ali al-Moussawi. The polls will go ahead elsewhere on April 20.
No group claimed responsibility for the Baghdad blasts, but Islamic State of Iraq, a wing of al Qaeda, has vowed to take back ground lost in its war with U.S. troops. This year the group has carried out a string of high-profile attacks.
Violence is still below the bloody height of the sectarian slaughter that killed tens of thousands after Sunni Islamists bombed the Shi'ite Al Askari shrine in 2006, provoking a wave of retaliation by Shi'ite militias.
But security officials say al Qaeda's local wing is regrouping in the vast desert of Anbar province bordering Syria and suicide bombers have carried out attacks nearly twice a week since January, a rate not seen for several years in Iraq.
Further complicating security, thousands of Sunni protesters are also rallying in Anbar against Maliki, whose Shi'ite-led government they accuse of marginalising their minority sect since the fall of Sunni strongman Saddam.
Syria's war next door is also whipping up Iraq's volatile mix. Iraq is exposed to a regional tussle for influence between Turkey, which backs Sunni rebels fighting President Bashar al-Assad, and Shi'ite Iran, the Syrian leader's main ally.
Unending political crisis
After Operation Iraqi Freedom promised to liberate the Iraqi people, Iraq has struggled with a decade that drove the country into sectarian mayhem which killed tens of thousands and turmoil of a young democracy emerging out of dictatorship.
Since the last election in 2010, Maliki's Sunni and Kurdish critics have accused him of consolidating his own authority, abusing his control of the security forces to pressure foes and failing to live up to a power-sharing deal.
The political turmoil has only worsened since American troops left Iraq in December 2011, removing the symbolic buffer of U.S. military power and weakening Washington's influence.
Iraq's Arab-led central government and the country's autonomous Kurdistan region, where ethnic Kurds have administered their affairs since 1991, are locked in a feud over control of disputed territories containing some of the world's richest oil reserves.
Both have sent troops from their respective armies to reinforce positions along their contested internal border.
Some of the tensions may be posturing before the provincial vote and parliamentary elections in 2014, and a full-scale Iraqi breakup looks unlikely. But after more than a year of crisis, rival Shi'ite, Sunni and Kurdish leaders are hardening positions along sectarian and ethnic lines.