BAGHDAD ø The United States has arrested a senior Iraqi commander in what was described as a blow to the newly-reconstituted National Guard.

Officials said the senior Iraqi National Guard commander was accused of helping Sunni insurgents in attacks on U.S. targets. They said this was the highest level case of infiltration of Iraq's military and security forces by the insurgency movement.

The U.S. military said Brig. Gen. Talib Al Lahibi was arrested in Diyala northeast of Baghdad on Sept. 23.Officials said Al Lahibi had served as an infantry officer during the Saddam Hussein regime, Middle East Newsline reported.

Officials said Al Lahibi, acting head of the ING in the Diyala province, was accused of supporting Sunni insurgents in their campaign against the U.S.-led coalition. They said the commander was believed to have accepted money and other support for providing information on U.S. troop movements.

A U.S. military statement on Sunday announced the arrest of Al Lahibi. The statement said the ING commander maintained "associations with known insurgents."

The arrest of Al Lahibi was regarded as a major blow to the ING. The United States has been accelerating training and equipping efforts to ensure the reconstitution of Iraq's security forces for operations against insurgency-controlled cities. Officials said a major part of the effort comprised the formation of a command structure.

On Monday, three Iraqi National Guards officers were killed in a car bombing in Mosul. In Baghdad, Iraqi insurgents fired mortars that struck a police academy in Baghdad.

In September, the U.S. Defense Department described plans to allocate $3.46 billion for the development of the ING and other Iraqi military and security forces. The plans were meant to add another 20 battalions to the current 45 battalions in the force.

The U.S. military has sought to eradicate high-level corruption in the Iraqi police and security forces. In August, the United States disbanded the Faluja Brigade of the ING after it was found to have supported insurgents in that Sunni city. Earlier, the U.S. Marines arrested the police chief of the Anbar province near the Syrian border in connection with insurgency attacks on U.S. forces.

U.S. officials said the arrest of Al Lahibi would not hamper plans to expand the ING. But they said the U.S. military expected Sunni and Shi'ite insurgents to increase efforts to infiltrate and undermine Iraq's military and security forces ahead of national elections in January 2005.

"I don't think Iraq will have a perfect election," U.S. Central Command chief Gen. John Abizaid said in a television interview. "We're going to have to fight our way all the way through elections and there'll be a lot of violence between now and then."

Officials said the military plans to regain control of the Sunni cities of Ramadi and Samara in the first step of the stabilization effort. They said Faluja would be saved for last.

"Ramadi and Samara, I think we'll get those back under control, and then we'll have to deal with Falujah," Secretary of State Colin Powell said.