By Alister Bull

BAGHDAD, July 14 (Reuters) - Eight people were killed by car bombs in Shi'ite districts of Baghdad on Saturday and eight other Shi'ites were shot dead in their beds, Iraqi police said.

U.S. forces are targeting al Qaeda militants blamed for stoking sectarian hatred between majority Shi'ite and minority Sunni Arabs. Militants used several women and children as a human shield during a clash north of Baghdad, the military said.

The militants eventually set their hostages free, and U.S. troops called in an air strike that killed at least six fighters during the heavy gun battle that followed, the military said.

Gunmen shot dead an Iraqi who worked as a translator for Reuters in Baghdad this week, his family said on Saturday, asking that his name not be given for fear of reprisals.

He was the third person working for Reuters killed in Baghdad this week.

U.S. and Iraqi forces have launched a big security operation since mid-June, coinciding with the arrival of the last of 28,000 troops ordered to Iraq by U.S. President George W Bush.

Washington hopes they can help quell sectarian bloodshed, allowing Shi'ite Prime Minister Nuri al-Maliki to deliver political reforms aimed at improving relations with Sunnis, who form the backbone of an anti-U.S. insurgency.

But U.S. public opinion has swung firmly against the war and two senators from Bush's own Republican Party called on Friday for a plan to start bringing troops home before year-end.

Bush wants more time for the clampdown to show results and says there will be no change in course before a September progress report from his top Iraq commander, General David Petraeus, and the county's U.S. ambassador Ryan Crocker.

They will review efforts to disrupt Islamist Sunni al Qaeda bombing cells blamed for devastating attacks that have pushed Iraq to the brink of civil war.

CAR BOMBS, TORTURE

There have been fewer very large car bombs in the capital in recent weeks, but violence continued to flare.

Seven people were killed and 15 wounded by a car bomb parked near vehicles queuing to buy petrol in the busy Shi'ite neighbourhood of Karrada in central Baghdad, police said.

A car bomb earlier reduced an apartment building to rubble in a Shi'ite district of southern Baghdad.

Police said one person was killed and four others were wounded when a parked minivan filled with explosives blew up next to the residential building.

It was not clear how many people lived in the building, but the exodus of families fleeing sectarian violence has made half-abandoned dwellings a common sight in the city.

Local residents helped clear debris as firefighters doused fierce flames from burning cars. Two crutches lay close to small pools of blood near a damaged car.

Twenty one bodes were found dumped around the capital on Friday, police said. Many bore signs of torture, evidence of tit-for-tat sectarian killings.

South of the capital, police said eight Shi'ite men from the same family were shot in their beds in a pre-dawn attack.

They said gunmen stormed the family home in the mainly Sunni town of Jbela, 65 km (40 miles) south of Baghdad, wounding three other men but sparing the women and children.

A U.S. soldier was killed by a landmine south of Baghdad while on foot patrol, the U.S. military said. More than 3,600 U.S. forces have been killed since the 2003 invasion, including more than 30 so far this month.

U.S. commanders warn casualties may rise as forces spread out into riskier areas to confront militants and insurgents.

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