The bodies were found on a road near the restive city 65km northeast of Baghdad.
The police said the bodies, which have not been identified, were tossed out on the side of the road near the village of Mulla Eid, about 30km southwest of the Baquba, notorious for its sectarian killings.
Since the dynamiting of a Shia shrine in Samarra on February 22, large numbers of corpses have been found in Baghdad and surrounding provinces.
A 13-year-old boy was also killed on Sunday by a roadside bomb as he walked to school in the southern city of Basra.
According to police, the boy was killed when a bomb in front of his school detonated at 7.30am as pupils arrived for class on Sunday in al-Muwafaqiya neighbourhood.
The attack is the latest in a recent series of violent acts targeting Iraqi citizens.
"We need very badly to form this unity government as soon as possible. We all know the polls show declining support among the American people"
In Baghdad, a bomb exploded in front of a house in the central neighbourhood of Karrada, killing one woman, wounding two of her sisters and a man next door. A truck driver was shot dead in west Baghdad.
In Samarra, the US and Iraqi forces arrested the imam of al-Rabat mosque in a raid on his house.
Police discovered 13 handcuffed and bullet-riddled bodies.
Ten were found in the Dora area of south Baghdad, another in the northern district of Hurriya and two in the city of Baquba, 60km northeast of Baghdad.
Iraqi officials and police continue to be targets as well.
Security guards working for the Iraqi finance minister were attacked while driving to pick up the minister in western Baghdad. One guard was killed and a bystander wounded, police said.
In a similar incident, guards were wounded in a bomb attack on their way to pick up the mayor of Baquba.
Several gunmen killed a police officer and his cousin as they walked in a region 25km north of Baquba, and a farmer was killed in the nearby town of Buhriz.
A group of visiting US politicians led by the Republican senator John McCain voiced alarm a day earlier about increasing sectarian violence in Iraq and told political leaders that American patience was growing thin and that they needed to urgently overcome their stalemate to form a national unity government.
It was the second high-level US delegation in less than a week delivering the same message as the Bush administration strives to overcome the political impasse that threatens the start of a possible American troop pullout this summer.
Iraqi citizens are increasingly
On Tuesday, a delegation led by Senator John Warner, the Republican who is chairman of the Armed Services Committee, delivered the same message, saying the unease back home could force US politicians to press for a reduction in American troop strength if the government delay were prolonged.
"We need very badly to form this unity government as soon as possible. We all know the polls show declining support among the American people," McCain said at a news conference on Saturday.
Elsewhere on Sunday, Iraqi authorities arrested a police major accused of taking part in death squads, according to officials from the interior ministry.
They said Arkan al-Bawi, who works in Diyala province northeast of Baghdad, was detained after visiting the ministry.
Sunni Arabs accuse the Shia-led government of sanctioning death squads, a charge the government denies.
Al-Bawi, whose brother is the chief of police in Diyala, was accused of operating in death squads in Baquba.