A top U.S. Air Force general said Sunday that reports of civilian casualties in Iraq as a result of American military action were exaggerated.

"I would tell you first off I don't believe most of it and I am very much aware that some of that has been staged," said Lt. Gen. Walter E. Buchanan III, Commander of the 9th U.S. Air Force and U.S. Central Command Air Forces.

Buchanan, speaking to The Associated Press on the sidelines on the annual Dubai Air Show, said the U.S. Air Force was doing everything necessary to minimize civilian casualties.

"We are very, very careful, and we use precision-guided munitions. We only drop the weapons we have to and they are always the smallest weapons possible," he said.

There are no official figures on civilian casualties in Iraq. A U.S. military spokesman told the AP last month that as many as 30,000 Iraqis may have died during the war, which began with the U.S. invasion in March 2003.

"We control the collateral damage, and we have very strict rules of engagement to guide us through minimizing noncombatant injuries and death," Buchanan said.

The general said bombing operations near the Syrian border had intensified recently.

"That is true especially as you go out toward the Syrian border. There are many operations there to counter the insurgent activity and interdict those that are trying to use the Syrian border as an entry point into Iraq," he said.

Buchanan said the United States had no evidence that Syria was involved in the infiltration of insurgents in Iraq.

"Our only concern with Syria is the number of terrorists infiltrating through porous borders with Iraq," he said.

Buchanan also disputed reports that the U.S. military was using white phosphorous against civilians in Iraq.

"It is purely used as a marking round, not as a weapon. It marks the target so it becomes very clear," he said.

Pentagon officials acknowledged Tuesday that U.S. troops used white phosphorous as a weapon against insurgent strongholds during the battle of Fallujah in November 2004. At the same time, they denied an Italian television news report that the spontaneously flammable material had been used against civilians.

The British government said Wednesday its military uses white phosphorous in Iraq but only to lay smoke screens.

Use of white phosphorous is not banned but is covered by Protocol III of the 1980 Convention on Conventional Weapons. The protocol prohibits use of the substance as an incendiary weapon against civilian populations and in air attacks against military forces in civilian areas.

The United States is not a signatory to the convention. Britain is.