BAGHDAD - Almost 2,000 bodies were taken to Baghdad's morgue in July, the highest tally in five months of rising sectarian bloodshed which has forced the United States to boost troop levels in the capital to head off a civil war.

Morgue assistant manager Doctor Abdul Razzaq al-Obaidi said today that about 90 per cent had died violently.

"Most of the cases have gunshot wounds to the head. Some of them were strangled and others were beaten to death with clubs," he told Reuters.

The grim statistics came as a new poll showed the Iraq war had become more unpopular with Americans and four Iraqis suspected of involvement in the abduction of American journalist Jill Carroll were arrested by coalition forces.

The CNN poll showed that 60 per cent of Americans were against the US war in Iraq, the highest level of opposition since the 2003 invasion, and a majority would back a partial withdrawal of US forces by year's end.

Carroll was freed unharmed in March after 82 days in captivity. More than 200 foreigners and thousands of Iraqis have been kidnapped since the 2003 invasion.

The daily drumbeat of violence continues, claiming at least 16 lives and injuring 37 others in attacks around the country.

In Baghdad, five people were killed when gunmen opened fire on a street vendor grilling fish in the western district of Jamiaa, an Interior Ministry source said. Police also found nine bodies of civilians in various parts of the capital.

The July morgue toll of 1,815 marked a big jump over the 1,595 in June and is the largest since the aftermath of the February bombing of the Shi'ite Golden Mosque of Samarra, which triggered an explosion of sectarian violence.

Iraq's Health, Interior and Defence ministries consistently provide lower figures than those released by the morgue.

Figures from those ministries showed about 1,000 civilians were killed across Iraq in July in "terrorism" attacks.

Mounting sectarian violence has prompted the United States to reinforce troop levels in Baghdad, which is regarded as the key to security in the whole country but is increasingly divided along sectarian lines.

About 6,000 additional Iraqi forces and 3,500 US soldiers of the 172nd Stryker Brigade combat team are being deployed in the Baghdad area and are expected to start systematically clearing neighbourhoods of militants and insurgents.

US Major General William Caldwell, chief US military spokesman in Iraq, said on Wednesday that US and Iraqi forces had conducted operations against 10 death squads throughout Baghdad in the last week, and also found 222 roadside bombs.

Sunni Arab leaders have accused Shi'ite militias of running death squads, a charge they deny.

Prime Minister Nuri al-Maliki has vowed to confront the armed militias, but must tread carefully as some of these groups have close ties to parties in his government.

Maliki said a consensus was building between religious leaders and prominent tribes to condemn the killings, and he was echoed by US Ambassador to Iraq, Zalmay Khalizad.

But there were no signs of unity on the streets.

Three policemen were killed and another seven wounded when a suicide car bomber rammed his car into a police station in the former tourist area of Habaniya, 85 km west of Baghdad, local police said.

Five civilians died and 20 were hurt by a rocket attack in Baquba, north of Baghdad, which collapsed a three-storey building near to a mosque, police said.

In the restive province of Anbar, west of Baghdad, three US soldiers assigned to the 1st Brigade, 1st Armoured Division were killed in action, the US military said.

The US military separately said that two other servicemen were missing in Anbar after a US army Blackhawk from the 3rd Marine Aircraft Wing crashed on Tuesday during an area familiarisation flight, with six crew aboard.

Four others survived and were in a stable condition. It said the crash did not appear to have been the result of an attack.