"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," a Russian foreign ministry spokesman told AFP.

A Jordan-based diplomat, quoting Russian sources, told AFP in Amman that ambassador Vladimir Titorenko was injured. But a Russian journalist travelling with the group said the envoy had escaped a bullet through the windscreen while three diplomats had been injured, one seriously.

The foreign ministry spokesman said at least four or five people were hurt. It was not immediately clear who was responsible for the attack, he said.

US Central Command in Qatar said Iraqi forces controlled the area and "initial reports" indicated were there were no US or British troops nearby.

But the Russian television journalist said the convoy had been caught in a crossfire between US and Iraq forces.

"As we left the city we passed through Iraqi forces, who suddenly came under fierce fire," Rossia television correspondent Aleksander Minakov said in a telephone interview with his studio.

In Washington, General Peter Pace, vice chairman of the Joint Chiefs of Staff, said the Pentagon was investigating.

"There was no reporting by any ground unit of the coalition of any kind of contact" with the motorcade.

US officials had been warned in advance that the convoy would be heading out, he told CNN.

US Secretary of State Colin Powell also called his Russian counterpart Igor Ivanov to assure him that an investigation was underway.

The shooting is the latest in a series of incidents that have vexed US-Russian relations since the start of the war, which Moscow vehemently opposes, and came as US national security advisor Condoleezza Rice arrived in Moscow Sunday for meetings with top Russia in an effort to improve ties.

Russia was one of the last countries to keep its embassy in Baghdad open, but decided Saturday to pull out most of its diplomats as US troops closed in on Baghdad.

Recounting the incident, Russian correspondent Minakov said: "As we left the city we passed through Iraqi forces who suddenly came under fierce fire. Shells exploded 50 to 70 metres (yards) from us followed by automatic arms fire.

"I am 100 percent sure the Americans were the first to open fire," he continued:

"The Iraqis obviously started shooting back and we were caught in a crossfire," the reporter added.

The convoy was spending the night at Fallujah, 50 kilometres (30 miles) west of Baghdad, to tend the wounded and would continue to Syria Monday, the Russian spokesman said.

"The first three cars full of diplomats came under machine gun fire," Minakov reported: "The ambassador was lucky because a bullet went through windscreen between the driver and him.

"But three diplomats were injured, including one with a serious abdomen wound."

The group had not dared to raise their heads for 30 minutes during the exchange, the journalist went on.

They dressed the wounds of the injured and pulled out during a pause in the gunfire.

He said they later approached US armoured vehicles, which ignored their request for medical assistance, but the group made it to a hospital in Fallujah where two diplomats received first aid and the more seriously injured one was operated on, Minakov said.

Another witness told Russia's Interfax news agency from Baghdad that around 23 people were in the convoy. He had a different version, reporting two separate attacks.

After the first incident they later came upon a jeep convoy about 15 kilometres from Baghdad," 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.

SPACE.WIRE