A US soldier was sentenced to three years in jail for the murder of a wounded Iraqi teenager in Baghdad in August, the US military said on Saturday.

Having pleaded guilty a day earlier under a plea bargain that averted the risk of a death sentence, Staff Sergeant Johnny Horne, 30, from Winston-Salem, North Carolina, was sentenced by a panel of seven senior soldiers at a court martial in Baghdad. During the proceedings, his action was described as a ?mercy killing?.

He shot a youth who had survived an attack by US troops on a garbage truck which they suspected of being used by guerrillas during a Shi?ite uprising in Baghdad in August. US officials have been quoted as saying six other Iraqis also died.

A second US soldier is to face trial on related charges. Local people say the men were innocent garbage collectors. The trial, one of several brought against US troops for murder and other serious crimes, including abusing detainees at Baghdad?s Abu Ghraib prison, is held up by US commanders as a mark of good faith toward Iraqis that soldiers are accountable.

Horne was also reduced in rank to private and dishonorably discharged. The incident came during overnight clashes in the poor Sadr City district on August. 18 with militia loyal to Shi?ite cleric Moqtada al-Sadr. Local people identified the victim as Qassim Hassan, 16, who was working with relatives.

Earlier this week, US Army Captain Rogelio Maynulet was ordered to face a full court martial for the murder in May of a man wounded as troops pursued Sadr?s militiamen near Najaf. Maynulet says he too carried out a ?mercy killing?.

Many Iraqis who welcomed the invasion to overthrow Saddam Hussein last year, have grown to fear the US troops occupying their country, saying Americans in constant fear of attack often fire on the innocent by mistake. Thousands of Iraqis have been killed since the invasion, many, but by no means all, by rebels. In scattered violence in mainly Sunni Arab areas of the country on Saturday, a US aircraft dropped a 500-lb bomb on insurgents who attacked a US patrol in the northern city of Mosul, scene of much bloodshed in recent weeks.

The powerful blast shook the west of the city. There was an ?unknown number of enemy casualties? and eight soldiers were slightly wounded, US Lieutenant Colonel Paul Hastings said. Insurgents had set off a car bomb and then opened fire with rifles, rocket-propelled grenades and mortars on the unit as it tried to seize an arms dump. Troops later destroyed the weapons.

Three high-ranking Iraqi police officers were among those killed in other attacks. Gunmen assassinated a police brigadier and a colonel in Baghdad and a police colonel was one of two officers killed in an ambush near Ash Sharqat in the north.

A car bomb exploded in the ethnically divided northern oil capital of Kirkuk, wounding two soldiers and an interpreter, the US military said. The wounded were in a stable condition.

Election office hit

Security officials and civil servants have become prime targets for insurgents opposed to the US military occupation and to Iraqis working for the US-backed authorities. There are fears violence may increase before an election on January. 30.

A bomb damaged an office for election workers in the town of Zab, southwest of Kirkuk, wounding a civilian, police said. Seven Iraqi National Guards were killed in an ambush at Hit, west of the Sunni cities of Ramadi and Falluja. US forces emptied Falluja and destroyed its guerrilla bases last month.

But Ramadi, 110 km west of Baghdad, is still a militant stronghold. US Marines accused insurgents in there of firing on them from a hospital late on Friday. A US Marine was killed in the region on Saturday, the US military said, giving no further details.

Falluja, once home to some 300,000 people, is almost a ghost town but still sees sporadic clashes between US troops and guerrillas. US forces let an aid convoy into the city to deliver supplies. But it left before nightfall due to fighting.

?We found that the security situation is still fragile?, said Iraqi Red Crescent chief Saed Ismail. While people in the city have complained of shortages, some 200,000 others living as refugees are impatient to go home. The US military says it has nearly finished hunting rebels and weapons and will then allow residents to return in stages.