THE CONFLICT IN IRAQ: SAUDI ROLE IN INSURGENCY - Iraq insurgency said to include many Saudis - They outnumber other foreigners, and half join as suicide bombers, a senior U.S. officer says.

BAGHDAD — Although Bush administration officials have frequently lashed out at Syria and Iran, accusing it of helping insurgents and militias here, the largest number of foreign fighters and suicide bombers in Iraq come from a third neighbor, Saudi Arabia, according to a senior U.S. military officer and Iraqi lawmakers.

About 45% of all foreign militants targeting U.S. troops and Iraqi civilians and security forces are from Saudi Arabia; 15% are from Syria and Lebanon; and 10% are from North Africa, according to official U.S. military figures made available to The Times by the senior officer. Nearly half of the 135 foreigners in U.S. detention facilities in Iraq are Saudis, he said.

Fighters from Saudi Arabia are thought to have carried out more suicide bombings than those of any other nationality, said the senior U.S. officer, who spoke on condition of anonymity because of the subject's sensitivity. It is apparently the first time a U.S. official has given such a breakdown on the role played by Saudi nationals in Iraq's Sunni Arab insurgency.

The situation has left the U.S. military in the awkward position of battling an enemy whose top source of foreign fighters is a key ally that at best has not been able to prevent its citizens from undertaking bloody attacks in Iraq, and at worst shares complicity in sending extremists to commit attacks against U.S. forces, Iraqi civilians and the Shiite-led government in Baghdad.

The problem casts a spotlight on the tangled web of alliances and enmities that underlie the political relations between Muslim nations and the U.S.

Complicated past

In the 1980s, the Saudi intelligence service sponsored Sunni Muslim fighters for the U.S.-backed Afghan mujahedin battling Soviet troops in Afghanistan. At the time, Saudi intelligence cultivated another man helping the Afghan fighters, Osama bin Laden, the future leader of Al Qaeda who would one day turn against the Saudi royal family and mastermind the Sept. 11 attacks on New York and the Pentagon. Indeed, Saudi Arabia has long been a source of a good portion of the money and manpower for Al Qaeda: 15 of the 19 hijackers in the Sept. 11 attacks were Saudi.

Now, a group that calls itself Al Qaeda in Iraq is the greatest short-term threat to Iraq's security, U.S. military spokesman Brig. Gen. Kevin Bergner said Wednesday.