Car bombs and blasts in cities across Iraq, including two explosions at a checkpoint outside Baghdad's international airport, killed at least 33 people on Monday days before provincial elections.
No one claimed responsibility for the attacks in Baghdad, Kirkuk, Tuz Khurmato and other towns to the north to south, but al Qaeda's local wing is waging a campaign against Shi'ites and the government to stoke sectarian confrontation.
Iraqis will vote on Saturday for members of provincial councils in a ballot that is seen as a test of political stability since the last U.S. troops withdrew in December 2011.
The ballot for nearly 450 provincial council seats will also be an important measure of Shi'ite Prime Minister Nuri al-Maliki's political muscle against his Sunni and Shi'ite rivals before a parliamentary election in 2014.
A dozen candidates have already been killed so far in campaigning, including two moderate Sunni politicians over the weekend.
Monday's attacks were mostly car bombs, including two blasts that killed two passengers at a checkpoint as they were on their way into the Baghdad airport site. Attacks on the heavily guarded airport and the fortified International Zone housing many embassies are rare.
"Two vehicles managed to reach the entrance of Baghdad airport and were left parked there. While we were doing routine searches, the two cars exploded seconds apart. Two passengers travelling to the airport were killed," a police source said.
The most deadly attack was in Tuz Khurmato, 170 km (105 miles) north of Baghdad, where four bombs targeting police patrols killed five people and wounded 67, officials said.
Later on Monday, 10 people were killed by a bomb at a car market in the Baghdad Shi'ite district of Sadr City and a blast outside a cafe in Khalis, a Shi'ite district in Diyala province.
SURGE IN ATTACKS
Iraqi violence has accompanied a long-running political crisis in the government that splits posts among Shi'ite, Sunni Muslim and ethnic Kurdish parties in an unwieldy, power-sharing coalition.
Critics dismiss Maliki, a former teacher who spent many years in exile in Syria and Iran, as an autocrat who has failed to live up to power-sharing agreements. He threatens to form a majority government to end the deadlock.
Violence is down since the height of sectarian slaughter that erupted in 2006-2007 when thousands were killed.
But al Qaeda's local wing, Islamic State of Iraq, and other Sunni Islamist insurgents tied to Saddam Hussein's outlawed Baath party, have managed to carry out at least one big coordinated attack a month since U.S. troops left.
Last year was first time the death toll had risen in three years and since the start of this year, al Qaeda has claimed a string of attacks on Shi'ite targets and security forces.
Al Qaeda is regaining ground, especially in the western desert near Syria's border, where it has benefited from the flow of Sunni fighters opposing Syrian President Bashar al-Assad.
Islamic State of Iraq says it has joined forces with the al-Nusra Front rebels fighting in Syria. Sunni insurgents, especially al Qaeda, see Baghdad's Shi'ite-led government and Assad as oppressors of Sunnis.
Insurgents are also tapping into Sunni frustrations. Many Iraqi Sunnis feel sidelined since the overthrow of Saddam and the rise of the Shi'ite majority. Security experts say al Qaeda is seeking to use that as a recruiting tool among Sunnis who see themselves victimized by security forces.