The fatal attack happened in Al-Madinah, a village some 50km north of the southern city where the soldier was serving in the International Stabilisation Force.
Meanwhile, in Baghdad, occupation soldiers came under repeated attack as tension among the Iraqi people continued to mount over a lack of drinking water, inflated gasoline prices and growing joblessness.
Services in the city of five million remain below pre-war levels.
Two US soldiers were shot as they left a restaurant Saturday evening. Though their injuries were not life threatening, escalating opposition strikes and an ever-increasing flow of injured comrades is sapping morale among US troops.
Attacks on US forces, mainly in Baghdad and the surrounding region where support for Hussein remains strong, have claimed the lives of 60 occupation soldiers since Washington declared major combat over on 1 May.
In another incident, a US helicopter was downed on Saturday in the unruly city of Tikrit, hometown of Iraq’s former President Saddam Hussein, an Aljazeera correspondent reported.
There was no information available on the cause of the crash and US soldiers prevented reporters from approaching the scene. Military spokespeople declined to comment on Sunday.
In Ramadi, 100km west of Baghdad, two Iraqi policemen were injured in a grenade attack, witnesses reported.
“Unknown assailants fired two grenades at the police station in Ramadi on Saturday at 2100 GMT, injuring two policemen,” AFP reported, citing Faris Mustafa.
Police chased one of the assailants, firing at him as he attempted to flee on a motorbike. He was shot dead, Mustafa said.
Ramadi is considered a stronghold of supporters of the former President, who hailed from the Sunni Muslim community that dominate the area.
They are very much embattled as Iraq's Shia majority, suppressed under Hussein’s 25 year reign, reasserts its will.
In a further blow to the US administration in Iraq, The North Oil company said repairs on a recently reopened then sabotaged pipeline taking oil to Turkey will take between two weeks and one month to complete.
Spiralling costs of rebuilding the war-ravaged country coupled with Iraqi resistance attacks is denting President George Bush’s popularity and making reconstruction ever-slower.
Central to US plans to rebuild the Iraqi economy is the repair of its oil infrastructure. The gulf country sits on the world’s second largest oil reserves and frequent sabotage is depriving it of badly needed export earnings.
For every day the pipeline to Turkey remains out of action, Iraq loses $6 million in earnings.
Iraq is currently exporting 700,000 barrels per day from its second main outlet, Basra. Sabotage and looting since the overthrow of Hussein have left just 150 of 700 oil wells in working order, officials have said.
“We were happy at first when the Americans came,” shop owner Jasm Kathai, 40, told AFP. “Now they should keep out, no one wants them around.”