A string of attacks across Iraq, including a coordinated wave of evening bombings in Baghdad, killed at least 45 people Monday as al-Qaida claimed responsibility for a recent spate of rare suicide attacks in the relatively peaceful Kurdish north.

Monday's bombings marked the third day in a row that insurgents were able to unleash attacks powerful enough to claim fatalities numbering in the dozens. The mounting bloodshed is heightening worries that the country is returning to the widespread sectarian killing that marked the years following the 2003 U.S.-led invasion.

A rapid-fire wave of bombings that rocked the Iraqi capital shortly after nightfall struck at least eight different neighborhoods, according to police officials, who provided casualty tolls. The force of one powerful blast, a car bomb explosion in the Bab al-Sharji neighborhood that killed four and wounded 11, rattled windows in central Baghdad.

More than 5,000 people have been killed since violent attacks began accelerating in April, including more than 50 Shiite pilgrims slain in a Baghdad suicide bombing Saturday and 12 children killed the following day when a vehicle packed with explosives blew up next to their school in the north of the country.

Amnesty International condemned the recent spate of killings as "a deplorable turn in the current surge in violence."

"These latest attacks are war crimes and are part of a widespread attack against civilians in Iraq that amounts to crimes against humanity," said Hassiba Hadj Sahraoui, the group's program director for the Middle East.

Monday's deadliest attack happened when a car bomb and roadside bomb exploded in a market and nearby parking lot in the northern Shiite district of Husseiniya, killing seven and wounding 21.

Car bombs also hit the mainly Shiite neighborhoods of Zafaraniyah, with four killed and 11 wounded, Alam, with two dead and 10 wounded, Obeidi, with five killed and eight wounded. Another bomb exploded outside a Zafaraniyah coffee shop later in the evening, killing three and wounding 10.

Confessionally mixed neighborhoods were also hit. A roadside bomb hit a commercial street in Kam Sarah, killing three and wounding eight, and the eastern Baghdad al-Jadidah, killing five and wounding 14.

Another car bomb exploded in shopping streets in the mainly Sunni neighborhood of Dora, killing four and wounding eight, and in the mostly Sunni area of Sadiyah, killing three and wounding 10.

Earlier on Monday, bombs targeting patrols of pro-government, anti-al-Qaida Sunni militia members outside Baghdad killed five and wounded 10, police said. The militiamen are a frequent target for al-Qaida, which considers them traitors.

Hospital officials confirmed the casualties. The authorities spoke on condition of anonymity because they weren't authorized to brief reporters.

There was no immediate claim of responsibility, but coordinated bomb blasts in civilian areas are a frequent tactic by al-Qaida's Iraq arm.

Earlier, al-Qaida claimed responsibility for rare suicide attacks last month in the relatively peaceful self-ruled Kurdish region, underlining the terror group's growing strength across the country.

The Sept. 29 twin suicide car bombs hit a complex housing the regional Interior Ministry and other security agencies in Irbil, the capital of the Kurdish region, killing at least six Kurdish troops and wounding more than 30 others. The attacks were the biggest in the Kurdish region since 2007, when a suicide truck bombing hit the same ministry, killing 14.

In a statement posted Monday on a militant website, the group, known as the Islamic State of Iraq and the Levant, said the attacks were retaliation for statements by regional President Massoud Barzani expressing readiness to help the Shiite-led central government in Baghdad in its fight against insurgents, and for his offer to assist Kurdish militias in neighboring Syria.

Al-Qaida-linked militants in Syria have been fighting ethnic Kurds in Syria's northeast.

Since 2003 U.S.-led invasion, the Kurdish region in northern Iraq has been relatively peaceful compared to the rest of the country, making it a major draw for foreign investors looking to gain a foothold in Iraq.

The authenticity of the statement by al-Qaida's Iraq branch could not be independently verified but it was consistent with the group's earlier statements.

Also Monday, Iraq's parliament said in a statement that lawmakers set April 30 as the date for holding national elections. Iraq's last national elections were held in March 2010. It took political rivals nine months to form a government. Since then, the Defense and Interior portfolios have been held by embattled Prime Minister, Nouri al-Maliki, because of ongoing political wrangling.

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Associated Press writer Sinan Salaheddin contributed reporting.

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