Baghdad, Iraq ? Two car bombs wounded American and Iraqi troops Sunday near the capital and hours later the U.S. military announced the arrest of a senior Iraqi National Guard commander on suspicion of ties to insurgents, underscoring the challenges to building a strong Iraq security service capable of restoring stability.

The two attackers who died in the twin blasts tried to ram their cars into a National Guard base in Kharma, a town on the outskirts of the insurgent stronghold of Fallujah, a U.S. military official said on condition of anonymity.

The number of U.S. and Iraqi casualties was not immediately clear, but a statement from the U.S. Marines said there were no serious injuries among American troops at the base.

The National Guard is the centerpiece of U.S. plans to turn over security responsibilities after elections slated for January, and guardsmen have been targeted repeatedly by insurgents who are trying to undermine Iraq’s interim government and drive out the U.S.-led coalition.

But the threat may not only come from outside the force. Guard Brig. Gen. Talib al-Lahibi, who previously served as an infantry officer in Saddam Hussein’s army, was detained Thursday in the province of Diyala, northeast of Baghdad, a U.S. military statement announced.

The statement provided no details, but said he was suspected of having links to militants who have been attacking coalition and Iraqi forces for 17 months.

Meanwhile, an Egyptian diplomat and two British Muslim leaders urged religious leaders here to help secure the release of hostages.

Egyptian official Farouq Mabrouk sought help for six Egyptian telecommunications workers abducted with four Iraqis last week. Mabrouk refused to speak to reporters after his 30-minute meeting with Harith al-Dhari, who heads the Association of Muslim Scholars, a conservative organization that has helped win the release of other foreign captives.

Gunmen abducted two of the Egyptians on Thursday in a raid on their firm’s Baghdad office — the latest in a string of kidnappings targeting engineers working on rebuilding Iraq. Eight other employees, four Egyptians and four Iraqis, were seized Wednesday outside of Baghdad.

Two senior officials of the Muslim Council of Britain were in Baghdad seeking freedom for hostage Kenneth Bigley, a British civil engineer kidnapped Sept. 16 with two Americans who were later beheaded.

After meeting with Muslim and Christian leaders, Daud Abdullah and Musharraf Hussain told reporters, “We cannot hold a British citizen responsible for what (British Prime Minister) Tony Blair did.”