Armed assailants killed four soldiers at the al-Siniya base west of the northern oil refinery town of Baiji on Saturday, said Iraqi army captain Toufik Khalaf.
In a separate incident, two soldiers were killed when armed men attacked an Iraqi army checkpoint in al-Dhuluiyah, 70km north of Baghdad.
An Iraqi translator for US forces was also shot dead on Saturday while in front of his house in al-Sharquat, 300km north of the capital. Meanwhile, a worker from the Dura refinery was gunned down in his car.
Spy drone downed
Meanwhile, an Iraqi group calling itself the Islamic Resistance Movement Twentieth Revolution Brigades says it has downed a US spy drone in the Abu Ghraib district, west of Baghdad.
The group posted a video on the internet showing armed men firing a missile and then pieces of wreckage said to be parts of the drone.
The authenticity of the tape could not be verified by an independent source.
Italian forces out
Meanwhile, Italy has begun winding down its military presence in southern Iraq with the withdrawal of a battalion of more than 120 soldiers, a military spokesman says.
"Between 120 and 130 men from San Marco battalion have returned to Italy and will not be replaced," Lieutenant-Colonel Fabio Mattiassi, spokesman for the Italian contingent in Nasiriya, said.
The announcement appeared to confirm a report in Saturday's La Stampa newspaper and previous statements by Prime Minister Silvio Berlusconi that Italy would recall 300 soldiers from its 3000-strong contingent operating under British command in southern Iraq.
The Italian Carabinieri patrol the
streets in Nasiriya
Berlusconi faced massive protests at home when in June 2003 he committed Italian soldiers to Iraq.
A bombing on an Italian police base in Nasiriya on 12 November 2003 killed 17 Italian soldiers and two civilians, and wounded 20 others. Al-Qaida claimed responsibility for the attack.
An Italian soldier was killed and 12 others injured in later clashes with Shia militias in the city.
Italian journalist Enzo Baldoni was kidnapped in August 2004 and murdered after the Italian government rejected an ultimatum to withdraw its troops from Iraq.
Indiscriminate US fire?
Residents of Nasaf, a town just outside Ramadi, west of Baghdad, said a roadside bomb exploded next to a US armoured patrol as it passed near the Ibn al-Jawzi mosque shortly after prayers on Friday.
The attack was followed by heavy US gunfire which left 15 Iraqis dead and 17 wounded, residents said.
US troops opened fire, the residents said, shooting towards those emerging from the mosque.
Munem Aftan, the director of Ramadi General Hospital, said 15 people were killed, including eight children. Seventeen people were wounded.
Roadside bombs are the biggest
killer of US troops in Iraq
The US military denied troops had opened fire indiscriminately.
"Indiscriminate US fire on civilians? No, nothing even resembling this occurred," Captain Jeffrey Pool, a marines spokesman in Ramadi, said in an emailed reply to questions.
He did not say whether an attack on a US patrol had occurred or whether any US troops were wounded.
Rights groups' concerns
The death toll was initially reported as two dead, but doctors said it had risen sharply overnight, with several of the severely wounded succumbing to their injuries.
Iraqi civilians frequently complain that US troops open fire indiscriminately after they are attacked.
Civilians have been shot and killed
at US army roadblocks
The US military says it does everything possible to avoid civilian casualties and is careful to respond to attacks in a measured fashion.
Human rights groups have documented scores of cases in which civilians have been shot and killed after approaching US military roadblocks too quickly, or not following instructions to keep away from US military convoys as they pass.
Roadside bombs - large or small amounts of explosives buried in the side of the road and detonated as US vehicles pass - are the biggest killer of US soldiers in Iraq.
A US general said on Friday that roadside bomb attacks on US supply convoys in Iraq had doubled in the past year, although the number of casualties had declined because of increased use of armoured vehicles.
A car bomber has blown himself up in front of a US military vehicle in south Baghdad on Saturday killing one civilian, an Interior Ministry official said.
"The attack occurred when the US military vehicle was tracing an IED (improvised explosive device) in the al-Dura neighbourhood," the official said.
"A bomber drove a car and blew it in front of the US vehicle. We do not know if there were any US casualties, but one civilian was killed and one wounded."
There was no immediate confirmation of the incident by the US military.
Attacks against US forces have surged recently with about 50 soldiers killed in the past three weeks.