Iranian officials say one of their senior diplomats has been shot dead in Baghdad.

Iran's state-run news agency, IRNA, identified the slain diplomat as Khalil Nai'imi, the embassy's cultural and press attache.

He was killed when unknown assailants opened fire on his car Thursday, near the Iranian embassy. There has been no claim of responsibility.

The killing came as a special Iranian delegation is in Iraq to help mediate an end to a standoff between U.S.-led coalition authorities and radical Shi'ite cleric Moqtada al-Sadr. The cleric's militia has clashed with coalition forces in central and southern Iraq.

The top U.S. military officer, General Richard Myers, who is visiting Iraq, said Moqtada al-Sadr and his militia are not leading a Shi'ite uprising, but are using fear and terror to try to control local government and police.

U.S. General Ricardo Sanchez repeated U.S. assertions that the extremist cleric would be dealt with either through capture or death, and his influence would be eliminated.

General Myers also addressed negotiations in the restive city of Fallujah, where Marines have battled insurgents for nearly two weeks. He said U.S. civilian administrator for Iraq, Paul Bremer, and others are still trying to negotiate a peaceful end to that insurgency.

The general also said that given the current security situation, U.S. commanders have asked for and will receive more troops.

In a separate development, the U.S. military says one American soldier was killed and five wounded in two attacks on convoys near the Iraqi city of Samarra on Thursday.