Two of al-Mahdi's guards were killed in a roadside bomb on Monday 120km north of Baghdad as they escorted the family of the Shia vice-president, an official source said.
None of his family members were hurt in the attack, the source added.
Three Iraqi soldiers were killed and two were wounded in another attack on Monday at a checkpoint near Baquba, also north of Baghdad, an Iraqi military source said.
The source said armed men attacked the position south of Baquba with grenades and small arms fire, killing three soldiers and seriously wounding two others.
The attack took place near the village of Bohruz, 15km south of Baquba, the main town in Diyala province.
Muhammad Husain, a member of the municipal council of al-Khaliss, just north of Baquba, and his driver were shot dead by armed men, a military source said.
Three civilians were killed in a roadside bomb in Tikrit, 180km north of Baghdad, a police officer said.
Also on Monday, Canadian Prime Minister Paul Martin revealed that an Iraqi-Canadian businessman kidnapped in Baghdad earlier in August had been killed despite efforts to pay a ransom.
Martin warned all Canadians in Iraq to leave Iraq as he condemned the murder of Zaid Meerwali, 32, who was kidnapped from his Baghdad home on 2 August.
"It is with both profound sadness and abhorrence that I learned of the circumstances of his death ... Canada vehemently condemns this barbaric crime"
Canadian prime minister
"It is with both profound sadness and abhorrence that I learned of the circumstances of his death," Martin said.
"Canada vehemently condemns this barbaric crime, and remains committed to working both bilaterally and multilaterally to help build a prosperous and peaceful democracy in Iraq," he said.
Meerwali, who held dual Iraqi-Canadian citizenship, returned to Iraq from exile after the fall of Saddam Hussein's government in April 2003.
His kidnappers demanded a $250,000 ransom, according to his family.
His nephew offered them $200,000, but after not hearing back from them, he circled area hospitals and made the grim discovery that his uncle had been killed.
In Baghdad on Monday, one Iraqi soldier was killed and another wounded when they came under fire in the eastern neighbourhood of al-Amiriyah, an Interior Ministry official said.
Five policemen and three civilians were injured by a mortar shell near the Interior Ministry, the source added.
Fifteen Iraqis, including six policemen, were wounded after a motorcycle-riding bomber wearing a explosive-laden belt blew himself up against a parked police patrol vehicle in the central Karadha district of Baghdad, the official said.
Two large explosions were also heard in central Baghdad late on Monday.
A group said it had downed a US
Army remote controlled drone
The blasts could be heard in the convention centre where the country's parliament was scheduled to meet late on Monday to approve the constitution.
Sirens wailed in the Green Zone, home to government offices and US military compounds, shortly after the blasts were heard.
Also on Monday, an Iraqi group claimed that it had downed an unmanned spy drone in Baghdad.
Al-Jaish al-Islami (The Islamic Army) group in Iraq claimed in a video tape that it had downed a US unmanned spy drone south of Baghdad.
The authenticity of the tape could not be verified by an independent source.
Three other Iraqi civilians were killed and six wounded when their vehicle hit a roadside bomb in the city of Tikrit, a police officer said.
In Samaraa, 125km north of Baghdad, another Iraqi soldier was gunned down and a colleague was wounded as fighters attacked their US-Iraqi patrol, an Iraqi army officer said.
An Iraqi woman was killed in Balad, 75km north of Baghdad, as a US-Iraqi military base was hit by a mortar attack, an army officer said.
The woman had gone to the base to inquire about her son who is a soldier and had not gone home for two months, the officer added.
A Turkish lorry driver was killed in Dujail, 40km north of Baghdad, as a roadside booby-trapped cow carcass exploded targeting a convoy of 30 trucks transporting supplies to the US military.
Five armed men were also killed in an attack on an Iraqi army position in the region of Shorgat, 300km north of Baghdad, while three others were killed in a shootout with police, a security source said.