A Jordan-based diplomat, quoting Russian sources, told AFP in Amman that ambassador Vladimir Titorenko was injured in the attack.

"The car convoy with members of the Russian embassy in Iraq, including the ambassador, came under attack leaving Baghdad in the direction of the Syrian border," the Russian ministry spokesman told AFP.

He said officials did not yet know whether the convoy came under attack from Iraqi or US-led coalition forces.

The Russian foreign ministry summoned the US and Iraqi ambassadors to Moscow "urgently and in a harsh way", the spokesman said, adding that it demanded "they take all possible measures to ensure the security of Russian citizens."

President Vladimir Putin has been informed of the incident, his spokesman Boris Gromov said.

The US Central Command in Qatar said it was looking into reports that its troops were the ones who attacked the Russian diplomatic convoy.

Titorenko left Baghdad for Damascus early Sunday as US troops advanced on the Iraqi capital. He was due to fly to Moscow later Sunday.

A witness told Interfax news agency from Baghdad that around 25 people -- mostly Russian journalists -- were driving in the convoy, which he said came under attack twice.

"In Baghdad, everything went calmly. When we left the city, we saw that there was fighting up ahead, so we decided to turn around and eight kilometers from Baghdad, we came under fire. Several people were injured," the witness told Interfax.

"We bandaged the wounded, left a car behind and kept going. But then around 15 kilometers from Baghdad we came upon a jeep convoy," he said.

"We stopped so as not to provoke them and we sent a car ahead with a flag to show who we were, but then we came under fire again," he told Interfax.

"Two more people were hurt -- thank God no one was killed.

"Then the jeeps left, we got on to the main road and now the main thing is to get to a hospital," he added.

Russia, one of the most fervent opponents to the US-led war, had kept its Baghdad embassy operational with a skeleton staff after withdrawing all non-essential personnel in the days leading up to the start of the bombing campaign on March 20.

Russia protested loudly last week when the building was nearly missed by US bombs.

SPACE.WIRE