Fighters opposed to the presence of foreign troops in Iraq set off a bomb Friday in a voting centre in Sharqat badly damaging it, police Lieutenant Colonel Farris Mahdi said.
No one was in the centre at the time of the blast, the second there in two months.
Sharqat, 300km north of Baghdad in Salahuddin province, is located in the Sunni Muslim heartland.
In other violence, a civilian, a policeman and two Iraqi soldiers were killed in separate incidents north of Baghdad.
Meanwhile, in the northern city of Mosul, a car bomb exploded Friday as a US convoy drove through the central district of Al-Muthanna, a witness said.
There was no immediate confirmation from the US military in Mosul, one of the trouble spots where fighters are expected to attempt to derail elections.
Thirteen people were injured in a
bomb attack on a Shia mosque
Elsewhere, a car bomb in north Baghdad has killed four people, while a further six Iraqis have died after a US tank smashed into the car they were travelling in.
The car bomb was detonated in Khan Bani Saad's Shia mosque immediately after Friday prayers, Aljazeera has learned. Up to 13 people were injured in the blast.
In the crash involving a US tank, eight people were also injured, three of them seriously. The wounded were transferred to hospital in Mugdadiya, in northeast Baghdad.
Separately, US troops burned down commercial shops in al-Radwaniya district, west of Baghdad, saying they came under attack from that area, Aljazeera has learned.
Attacks against US troops took
place across the country
Eyewitnesses said the US troops encircled the area and closed all roads to it before setting the shops ablaze.
Elsewhere, Aljazeera has learned that a US military vehicle was damaged by an explosive device planted on the highway in al-Dawra district, south of Baghdad. Witnesses said US troops flooded the area to evacuate the injured.
Fifteen Iraqi soldiers were kidnapped by armed men off their bus after they finished work on Friday at the Al-Asad US military base in the western province of Al-Anbar.
The men, who ride daily out of the Al-Asad airbase, about 150 kilometres west of Baghdad, were ambushed with rocket-propelled grenades and Russian-made RPK machine guns, said
police Colonel Fadel Abd al-Dulaimi.
"The soldiers were wearing civilian clothes and hiding their weapons under the seats ... The gunmen forced them to surrender and took them away," Dulaimi said.
"Intimidation factor is probably more prevalent in some places than other"
US Brigadier Jeffrey Hammond
Iraq's fledgling new security forces has been targeted by fighters, with attacks against them escalating since Iraq's transfer of sovereignty last June.
More than 1300 police, soldiers and national guards have been killed in Iraq since the fall of Saddam Hussein.
Election official killed
Late on Thursday, fighters shot dead another member of Iraq's electoral commission, west of Baghdad, an interior ministry official reported.
Abd al-Karim al-Ubaidi was the eighth electoral official to be killed in the run-up to elections scheduled for 30 January.
"Abd al-Karim Jasim al-Ubaidi, director of the voting station at al-Salam in al-Amil district, west of the capital, was gunned down on Thursday," said the official.
US officials say the expect a
surge in violence on election day
"He was hit by several bullets in the head," he added.
Last Tuesday, a senior commission official, Abd al-Lami, said seven members of the electoral body had been killed by fighters trying to disrupt the elections.
Kurdish officials killed
In a separate development, armed fighters killed three officials of a leading Kurdish political party in an ambush in the northern city of Mosul, another official of the party said on Friday.
Unknown attackers opened fire on the men's car on Thursday afternoon, Hashim Zibari of the Kurdish Democratic Party said.
Iraqi Kurds make up about 20%
of the population
Mosul, a predominantly Arab city northwest of Baghdad with a significant Kurdish population, has been one of several cities to see increased violence in the run-up to elections at the end of the month.
The Kurdish Democratic Party of Masud Barzani is one of two main factions representing Iraq's Kurds, who make up about 20% of Iraq's population.
Senior US officials and commanders in Baghdad were bracing for bloodshed on election day, anticipating car bombs, gunfire, mortars and rocket attacks.
"There are places here that are ugly. There are other places looking pretty dog-gone good," Brigadier General Jeffrey Hammond, a deputy commander of US troops in the capital, told reporters Friday.
"Intimidation factor is probably more prevalent in some places than other."
He cautioned that there was no guarantee that Iraq's election security plans were foolproof.
"A terrorist got into a base camp in Mosul and detonated a bomb and killed American soldiers. An insurgent would probably make every effort to penetrate (the polling stations)," Hammond said.
Concern has also been raised within the US embassy.
A senior American official told AFP that sections of western and northern Baghdad, including the Sunni Muslim Adhamiya district, would probably have low turnout due to the threat of fighters' reprisals against voters.