By Rania El Gamal

BAGHDAD, Sept 3 (Reuters) - After an explosive device torethrough the back of an armoured SUV carrying Chinese oil workersin Iraq in mid-July, security contractors said the U.S.military, not China's Daqing Petroleum, was the likely target.

The Explosively Formed Projectile, designed by Iran'sRevolutionary Guard Corp and often used by Shi'ite militia inIraq, shredded the rear of the car and exited on the other sidejust behind the passenger seat.

Three Chinese workers, who were helping develop Iraq'sbiggest oilfield Rumaila, received scratches and light burns.One security guard sitting in a front seat was hit by fragments.

Oil companies so far have shrugged off security concernsafter sealing a dozen deals in Iraq, which have the potential toquadruple the country's production capacity to rival Saudilevels of 12 million barrels per day.

"We have not had indications of international oil companiesbeing targeted in any sense, and I think at the end of the daythat will depend on what will be the motivation for thoseattacks," said a foreign oil executive working in Iraq.

U.S. military officials also said they did not think Shi'itemilitia were targeting oil workers or facilities in the July 15attack. "I think it is only a possibility," said Major GeneralStephen Lanza, the U.S. military spokesman in Iraq.

Yet after U.S. forces ended combat missions in Iraq on Aug.31 and cut their numbers to 50,000 7-1/2 years after theinvasion, some security firms and Iraqi officials are wonderingwhether Sunni Islamist insurgents and Shi'ite militia might nowfocus on the companies developing the vast oil reserves.

In a statement posted on a radical Islamic website lastmonth, a writer called for attacks on oil pipelines across Iraqon the grounds that oil was a main reason behind the invasion of"Muslim homes by atheist and disbelieving countries".

ALL DEPENDS ON OIL

Oil is viewed by Iraqi and U.S. officials alike as thepanacea for Iraq's ills. Everything depends on whether the OPECmember can secure its vital oilfields, export pipelines andrefineries.

The government has placed security forces and oil police onalert for attacks by al-Qaeda-linked groups as the U.S. endedcombat operations and intelligence reports warned of a threat tooil facilities.

"Of course there will be some attempts to target (oilfirms), but the areas where they work have good protection fromIraqi forces," said Safa al-Sheikh, acting National SecurityAdviser.

"We don't have accurate intelligence showing an increase (inattacks), but one thing we know about terrorists is that theyresort to all possible means and attack anybody they can."

Murder, intimidation and smuggling are also expected to risein places such as the southern oil hub of Basra, as the linebetween insurgency and crime becomes more blurred.

"We certainly haven't seen the end of terrorist attacks inIraq," said Kyle McEneaney, who heads the Middle East practiceat Ergo, an emerging markets consultancy.

"International oil companies may be affected somewhat, butthese companies are used to operating in difficult environments,and they understand the situation in Iraq."

'NO CRYSTAL BALL'

Overall violence in Iraq has fallen sharply in the past twoyears, and the Shi'ite south, where most current oil productiontakes place, is relatively peaceful. But still there areattacks.

Militants fired mortars in late July near the southernHalfaya oilfield, and one round landed 200 meters from an activeoil well, the U.S. Army said.

The Iraq-Turkey pipeline in the north, which carries arounda quarter of Iraq's oil exports, is regularly hit by sabotage,usually blamed on al Qaeda and the banned Baath party.

So far oil majors have shown no signs of a weakeningcommitment to Iraq. Companies are moving ahead with issuingtenders for work in their fields to reach the production targetsthey have set.

"None of us has a crystal ball to tell whether there will bean increase in violence or not with the withdrawal of the U.S.troops. I think it will primarily depend on the capability ofthe Iraqi security forces," the foreign oil executive said.

Although oil companies are used to tough conditions, aserious deterioration in security could still make some reducetheir staffing or even leave.

"So far it has had no impact on our operations," said theexecutive. "We will need to evaluate those incidents to be ableto judge what will be our next move. But then to be honest,everything is open."