In Babel province, south of Baghdad, a bomb targeted a bus carrying Shiite pilgrims heading to Karbala.
In Balad, north of Baghdad, a car bomb explosion targeting a bus of Iranian pilgrims killed 12 Iranians and 2 Iraqis, a police official said.
In the neighboring Orakzai tribal region, at least eleven people were killed when a roadside bomb targeted a bus carrying members of an anti-Taliban militia.
A mortar shell landed near a clinic in the town of Taji, north of Baghdad, killing two people, while a suicide bomber targeted a bus stop in Iskandariya, south of the capital, killing five people, AP said.
Taliban spokesman Zabihullah Mujahid said the first attack targeted a bus carrying police cadets and their instructors.
In mid-November, the militant group targeted a bus, killing 28 passengers.
"Masked armed men belonging to the terrorist Brotherhood targeted a bus of the armed forces... which led to the martyrdom of the Officer Yusri Mahmoud Mohamed Hassan, Ahmed Mohammed Alii said in a statement on Facebook.
Their targets included a bus depot, a market, the office of the local newspaper and the house of Manuel Carrascalao, the leader of the Council of National Timorese Resistance.
A Syrian official also said there were reports of a third blast Saturday targeting a military bus at the Yarmouk refugee camp in Damascus, but there were no details.
SOHR head Rami Abdulrahman said the suicide bombers targeted a military bus carrying Shiite militias who were changing guard there.
