FALLUJAH, Sept 7: The Iraqi cities of Fallujah and Sadr came under heavy US artillery fire and air strikes on Tuesday, leaving up to 140 fighters killed, the US marines said in a statement.

"Significant numbers of enemy fighters (up to 100) are estimated to have been killed in Fallujah while the rest were in Sadr city," the statement claimed. "We are responding after being under fire. We are hitting enemy positions in the city since 6.30pm. We are using aircraft and artillery fire," said Marine spokesman Lt Col T.V. Johnson.

Aircraft and artillery pounded the southern Shuhada district and industrial zone of Fallujah. Smoke mushroomed into the sky. War planes strafed the industrial zone. The general hospital had received an undetermined number of casualties and panic swept the city.

One ambulance driver said he had taken two dead and 15 wounded to hospital, while families fleeing the air raids said there were more corpses and wounded trapped in the zone under attack.

"Structures used as fighting positions by anti-Iraqi forces were repeatedly struck by defensive counter-fires. Many of these buildings erupted in secondary explosions that are characteristic of hits on weapons/ammunition caches," the military said.

Fallujah, which lies 50 kilometres west of Baghdad, is a bastion of the resistance against US-led forces in Iraq. A US air strike on a suspected militant safe house in the city killed 20 people one week ago.

Residents of Fallujah have often countered US claims that guerillas were being attacked, saying that those coming under fire were ordinary civilians. Seven US marines and three Iraqi national guardsmen were killed in a car bombing near the town on Monday - the worst single strike against the occupation forces in months.

The US military has resorted to artillery and aerial assaults on alleged hideouts in Fallujah since the city became a no-go zone for troops after an April offensive ended with an agreement for Iraqis to police themselves.

Within weeks, militants imposed full control over Fallujah, elbowing aside the local police and an ad hoc force of Iraqi army veterans, named the Fallujah Brigade, was formed to restore security.

BAGHDAD: Bloody clashes between US forces and Shia militiamen left more than 40 dead in Baghdad's Sadr City on Tuesday, while four US soldiers were killed in a spate of attacks.

Smoke was rising and US war planes roared overhead as armed members of radical leader Moqtada Sadr's Mehdi Army ran through the streets of the Baghdad slum after a night of fighting that left one US soldier dead and scores of Iraqis killed and wounded.

The Iraqi health ministry reported that 40 people were killed and more than 270 injured as a fragile week-long truce called by Moqtada Sadr unravelled. As troubles flared in the slum, the US military was mourning its dead from a flurry of attacks around Baghdad on Monday and Tuesday.

Militia fighters killed a soldier and wounded two others on Tuesday in a small-arms and rocket-propelled grenade attack Sadr City. Another three were killed in a string of attacks in the capital.

The attacks followed a car bomb explosion that killed seven soldiers and three Iraqi national guard near the restive city of Fallujah the previous day - the deadliest single strike in months for US troops.

The Fallujah attack was claimed by black-hooded men, gripping assault rifles, in the name of Jordanian fighter Abu Mussab al Zarqawi's militant group. The killings brought to 995 the total number of US military fatalities since the invasion of Iraq last year.

US tanks rumbled around the neighbourhood and automatic fire echoed on Sadr City's main Al Shuhader Street. Four military vehicles blocked off Al Hay square, site of Moqtada Sadr's main office.

On side streets, Mehdi army soldiers, dressed in their trademark black outfits and civilian clothes, planted bombs in the road. The US Army reported a string of attacks overnight on US forces in the den of the young radical who has organized a thousands-strong army of young and unemployed Shia men.

Sadr aide Sheikh Naim al Qaabi said 15 Mehdi Army fighters were killed and 62 wounded in the strife. Last night (Monday) was the most intense shelling of Sadr City since the Americans arrived in Iraq," he said, adding heavy aircraft fire lasted five hours. "The people are defending themselves against the occupation forces."

There was no confirmation from the Americans about airstrikes in the Shia neighbourhood. A mortar landed near a school as the battle raged, the military said. An uneasy calm had reigned in the district since the end of last month's three-week revolt by Moqtada Sadr against the Americans in Najaf.

Sadr's men had entered into negotiations with the Iraqi government to disarm and enter the political arena, but his right-hand men complained the Iraqi government had started arresting its followers last week despite the talks.

NARROW ESCAPE: Baghdad governor Ali al Haidri on Tuesday narrowly escaped a bomb assassination attempt on his life that left two civilians dead, officials said. "There was an attempt to assassinate the Baghdad governor," said interior ministry spokesman Colonel Adnan Abdul Rahman.

A police investigator on the scene in Baghdad's western Al Adel district said the bomb was a small booby trap device planted in a pothole, although the interior ministry described it as a car bomb. Some of Haidri's bodyguards were wounded, the governor said.

The deputy director of Karama hospital in Baghdad was also shot dead, the health ministry said. And in the northern city of Mosul, the son of governor for the northern Iraqi province of Niniveh was assassinated.

Leith Dureid Kashmula, 19, was shot several times in the chest by unknown attackers as he was alone in his car in western Mosul, said Hazem Gallawi, media adviser for the gover norate. A Turkish truck driver was killed when guerillas fired small arms at some petrol tankers parked outside Abbasi, 22 kilometres from guerilla bastion of Samarra. -Agencies