The bodies of four Iraqis working for a foreign company were also discovered near Kut, a city south-east of Baghdad, police said. The US military also retrieved the body of an executed Iraqi from a river north of Baghdad.
No further details were available on the circumstances of the latest deaths, but insurgents have been imposing their rule on several areas across Iraq and carrying out a campaign of intimidation among the population.
Fears that a major spate of attacks will wreck the milestone general elections on January 30, have prompted US and Iraqi forces to take special measures to prevent a bloodbath.
The government will declare a holiday for the January 30 vote and impose tight restrictions on movement, including a total ban on vehicles around polling stations, State Minister for the Governorates Wael Abdul Latif told reporters.
"Polling stations will be well safeguarded - no vehicles will be allowed anywhere near and there will be restrictions on traffic," he said. "There will be separate body searches for men and women."
Abdul Latif said vehicle travel would be limited between the provinces and inside each region, even among Baghdad's different neighbourhoods.
Abdul Latif acknowledged that the threat of insurgent attacks had compromised preparations for the poll in four of Iraq's 18 provinces.
Electoral commission chief Abdul Hussein Hendawi said that violence in Al-Anbar province, west of Baghdad, and Nineveh province around the main northern city of Mosul had prevented any registration of voters.
Voter registration would be carried out on polling day in those provinces, he said.
There was no let-up in the violence as the government unveiled its plans. A US marine was killed in action on Saturday south of Baghdad, the US military said in a statement.
"A US Marine was killed in action on January 15, while conducting security and stability operations in Babil Province," it said in a statement, without elaborating.
Five Iraqi soldiers and a policeman were shot dead in a string of insurgent attacks around the northern trouble spots of Samarra and Kirkuk, police said on Saturday.
Four Iraqi soldiers were killed when gunmen ambushed a checkpoint to the west of the Sunni bastion of Samarra, said Lieutenant Colonel Mahmud Mohammed.
In northern Samarra, another soldier was killed when gunmen attacked an Iraqi army patrol, said a police source on condition of anonymity.
Meanwhile, near a US base outside Kirkuk, a policeman was killed and four others wounded - one seriously - when insurgents attacked a police checkpoint, said General Turhan Yussef, police chief in the tense city.
An Iraqi member of the International Committee of the Red Cross was killed west of Baghdad on Saturday, the humanitarian organisation announced in Geneva.
The ICRC did not elaborate on the circumstances that led to his death.
Two mortar rounds hit a police station just outside the heavily fortified Baghdad compound which houses the interim government and the US embassy, wounding two civilians, medical sources said.
Meanwhile, an al Qaeda linked group on Saturday said it had kidnapped 15 Iraqi national guardsmen west of Baghdad.
"Your Mujahideen brethren managed yesterday to ambush the right hand of the crusader (US) forces in Iraq, the so-called pagan (national) guard forces, in the district of Hit, west of Baghdad," said a statement by the Army of Ansar al-Sunna posted on its website.
The authenticity of the statement could not be immediately confirmed.
"The heroes pounced on them like lions, and the cowards could only surrender. Thanks to God, 15 elements from the pagan guards were taken prisoner, along with their equipment," it added.
Police said on Friday that 15 Iraqi soldiers had been kidnapped by gunmen after finishing work at a US military base in the lawless western province of Al-Anbar.
Ansar al-Sunna split from radical group Ansar al-Islam, both of which are believed to have links with suspected al Qaeda operative Abu Musab al-Zarqawi.
However, Ansar al-Islam on Saturday denied it was behind the killing of an aide to top Shia cleric Ayatollah Ali al-Sistani, according to an Internet message.
Moreover, Portugal confirmed that it would withdraw its 120-strong military police contingent from Iraq on February 12, after seeing through its pledge to help provide polling day security.
The US-led coalition meanwhile came in for strong criticism from the British Museum for causing "substantial damage" to ancient Babylon, one of Iraq's most important archaeological sites.
Future excavations at the site have been compromised by its use as a military depot by US and Polish forces over the past two years, the curator of the museum's Ancient Near East department, John Curtis, said.
Curtis called on the Iraqi authorities to appoint an international team of archaeologists to compile a full inventory of the damage.