BAGHDAD ø The U.S.-appointed Iraqi leadership has again come under direct threat from insurgents.

On Monday, the president of Iraqi Governing Council was killed in a car bombing near a U.S. checkpoint in central Baghdad. Izzadine Salim was one of six Iraqis and the first IGC president killed in the suicide attack.

Salim was part of the Supreme Council of the Islamic Revolution in Iraq, the leading Shi'ite opposition to the Saddam Hussein regime. He was also known as Abdul Zahraa Othman, Middle East Newsline reported.

An unknown group, the Arab Resistance Movement, claimed responsibility for the assassination. The group made the claim on a statement on the Internet. U.S. military sources said the group could be linked to or directed by Abu Mussib Al Zarqawi.

It was the second time an IGC member was killed by Iraqi insurgents since the body was established in July 2003. On Sept. 20, 2003, Aquila Al Hashimi, one of three women on the 25-member council, was killed in an ambush near her home in Baghdad.

The IGC selected Ghazi Mashal Ajil Al Yawer to become president. Yawer, a Sunni Muslim civil engineer from Mosul, had been scheduled to take over the rotating presidency on June 1 from Salim.

U.S. military sources said the assassination appeared to be the work of Saddam loyalists in cooperation with Ansar Al Islam, the Al Qaida-aligned group believed to have been responsible for most of the suicide and car bombings in Iraq. The sources said the two groups have succeeded in infiltrating the security detail of the IGC in Baghdad and probably knew the schedule of arriving Iraqi ministers.

Officials said the coalition plans to establish a protective service for Iraqi leaders modeled after the U.S. Secret Service. They said the United States has provided the tools for security for IGC members.

Coalition Provisional Authority senior adviser Dan Senor said the coalition has provided funding, body armor, weapons, vehicles and training for the personal protective details of IGC members. But he said that not all protective details -- including that of Salim -- participated in the training.

Instead, Salim's security detail consisted mostly of cousins, nephews and other family members. The coalition has offered a six-week training program as well as a refresher course for security personnel. Officials said that so far, about 200 security officials for the IGC have attended the initial training, and about 40 have gone through the refresher training.

"Unfortunately, our records show that none of his [Salim's] personal security detail members ever participated in any of our training programs ø again, his choice," Senor said. "We make the resources available, we make the training available, but it is up to the individual general council members and the security details if they want to participate."

The United States was scheduled to relay sovereignty to the IGC on June 30. Officials said the assassination of Salim would not delay the handover.

"This will strengthen our resolve to continue the political process," Iraqi Foreign Minister Hoshiyar Zebari said. "This will not derail the process."