Gunmen used two vehicles, including a minibus, to block off the street in the upscale west Baghdad neighbourhood of Mansour where the Russians were driving.

The gunmen then opened fire on them, fatally wounding one before taking the rest.

The interior ministry has alerted police to be on the lookout for a car and minibus of Korean manufacture carrying four foreigners.

The Russian embassy had no comment on the attack.

Home to many embassies, the Mansour neighbourhood has been the scene of a number of attacks and kidnappings of diplomatic personnel, the most recent being of an Emirati diplomat on May 15.

The Algerian charge d'affaires and another diplomat were killed in Mansour in July 2005, while the charge d'affaires of the Bahraini embassy was wounded in the same month.

Also in July 2005, the Russian ambassador's convoy was attacked on the way to the airport, though the ambassador himself was not present.

According to the Iraqi foreign ministry there are 45 diplomatic missions active in the country.

Earlier seven policemen were killed and 10 people wounded by an insurgent attack on a checkpoint near the Iraqi city of Baquba, northeast of Baghdad, according to local police.

The insurgents threw hand grenades and fired rocket-propelled grenades and assault rifles at the Al-Razi checkpoint at the southwest entrance to the city at 1:00 pm (0900 GMT). Among the wounded were four policemen and six civilians.

The restive Diyala province has been the site of numerous large-scale attacks against police facilities.