An Iranian diplomat has been shot dead in the Iraqi capital Baghdad.
There are as yet few clues as to why the Iranian diplomat was targeted
First secretary Khalil Naimi was attacked while driving near the embassy. Correspondents have seen a bullet-ridden car with a body inside.
At this stage it is not clear who carried out the attack or whether the diplomat was specifically targeted.
An Iranian foreign ministry delegation is in Iraq to try to assist in the crisis over the rebel leadership of cleric Moqtada Sadr.
Naimi died immediately, foreign ministry official Mohammad Nouri told the Associated Press news agency in the Iranian capital Tehran.
An Iranian official in Baghdad told another agency, Reuters, that Naimi had been driving to the office when "three men drove up and shot him".
The Iranian delegation - now reported to be in Najaf - has brushed off suggestions it is mediating between the US and Mr Sadr, saying it is merely "assessing" the situation.
Iraqi negotiators, however, say Iranian officials are trying to help resolve the standoff.
Hussein Sedeqi is heading a delegation assisting in the Najaf crisis
Mr Sadr, who US forces have vowed to "kill or capture", is barricaded inside Najaf, which is Iraq's holiest city.
The US has massed 2,500 troops in readiness for an offensive, though both sides have said they want to avoid bloodshed.
Sporadic fighting has continued in another trouble hotspot, Falluja, between US marines and insurgents, despite a declared truce.
US warplanes are reportedly still carrying out missions above the city.
The Pentagon says at least 93 soldiers have died so far this month. Some 900 Iraqis are thought to have been killed in the same period.