Separately, a Kurdish officer in the Iraqi president's guard is alleged to have shot dead the head of a local radio station during a quarrel near the leader's east Baghdad residence, police said.
The police said Mohammed Bedwei was shot at a checkpoint by a lieutenant in the mostly Kurdish security detail for Jalal Talabani, an ethnic Kurd.
The accused killer was handed over to Iraqi security forces that have besieged the residency compound, police and state TV said.
Talabani suffered a stroke last year and is being treated in Germany. Few details have been released about his health since then.
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State-run TV showed Prime Minister Nouri al-Maliki arriving at the crime scene near the presidential palace. "All the people behind this should stand trial. Blood for blood and this is a violation of the law," he said
Meanwhile a series of blasts struck across the country. Police officials said the wave began with a roadside bomb in a commercial street in the northern city of Tikrit. Minutes later, a car bomb struck policemen who had arrived to inspect the site of the first blast.
Hours later, police said a suicide bomber rammed his explosive-laden car into a security checkpoint near the town of Adeim about 100 km north of Baghdad. Three civilians and three police were killed.
Also, a roadside bomb hit a military checkpoint near the northern city of Mosul, killing two soldiers and wounding three others, according to the police.
The Iraqi security forces are a favorite target for Sunni insurgents who attempt to undermine the Shiite-led government. Violence has spiked in Iraq since last April, a surge unseen since 2008. The relentless attacks have become the government's most serious challenge.