Seven bomb explosions have killed 28 people and wounded 67 in the Iraqi capital, police and medics said, as security forces battled fighters around the western cities of Fallujah and Ramadi.
The bloodiest attack on Monday occurred in the mainly Shia Muslim Abu Dsheer district in southern Baghdad, where a car bomb near a crowded market killed seven people and wounded 18.
Five of the bombings targeted mainly Shia districts of the capital, while two were in mostly Sunni areas.
No group claimed responsibility for the blasts. But Sunni fighters, some of them linked to al-Qaeda, are widely blamed for a surge in violence in the past year apparently aimed at undermining the Shia-led government.
Al-Qaeda fighters and their local allies seized control of Fallujah and parts of Ramadi on January 1, exploiting resentment among minority Sunnis against the government for policies perceived as unfairly penalising their once-dominant community.
Sporadic fighting again flared around Fallujah and Ramadi in Anbar province on Monday.
Anti-government tribesmen attacked an army barracks in Saqlawiya, 10km northwest of Fallujah, and destroyed two military vehicles, before army helicopter gunships forced them to retreat.
One of the attackers was killed and two wounded, police said. There was no word on casualties among the army.
Prime Minister Nouri al-Maliki, who faces a parliamentary election on April 30, has ruled out a full-scale army assault on Fallujah, urging tribesmen to drive al-Qaeda fighters from the city, where US troops occupying Iraq fought some of their toughest battles in 2004.
An Iraqi journalist, Firas Mohammed, was killed by a roadside bomb that exploded near a police station in Khaldiya, a town between Fallujah and Ramadi, on Sunday, police said. He had worked for the local television channel in Fallujah.
Ten journalists were killed in Iraq last year, the highest number anywhere except Syria, according to the New York-based Committee to Protect Journalists.
The latest violence came as security forces continued its operation against anti-government fighters in Ramadi, another city where swathes of territory have been outside of the authorities' control.
Deputy Interior Minister Adnan al-Assadi warned in a speech that armed groups fighting in Anbar had amassed "numerous and modern" weapons.
"They are enough to occupy Baghdad," he said. "Their target is not just controlling Fallujah or [the nearby town of] Garma, it is to topple the entire political process."