Two Russian civilian contractors were killed and five others wounded in an ambush near Baghdad on Wednesday when the bus they were traveling in came under attack, the Russian Foreign Ministry spokesman Alexander Yakovenko said.

Yakovenko told Rossiya, the state-run television network, that the two killed were employees from Russia's Interenergoservice, which is working to restore energy supplies to the war-torn country.

"According to the Iraqi Interior Ministry, unidentified assailants attacked the bus carrying Russian specialists early in the morning," Yakovenko said. "Two Russian specialists were killed in the incident, and another five were wounded. Two Iraqis were also killed."

He said the wounded were currently receiving medical treatment at a Baghdad hospital, adding that the Russian Embassy and the Iraqi authorities are investigating the incident.

Meanwhile, an official from Interenergoservice said two of its employees were killed and another six wounded in the attack.

The attack was the second of this kind this year. On May 10, a group of armed men attacked Russians working for Interenergoservice as they were returning from work. One Russian was killed and two others were abducted in the attack. A week later the two hostages were released.

Three Russians and five Ukrainians working for Interenergoservice were abducted in Iraq on April 12, but were released unharmed the next day.

Since the attack on May 10, Interenergoservice has withdrawn 112 of its employees from Iraq. However, some 230 Interenergoservice employees are still staying in Iraq.

A source with the Foreign Ministry said Interenergoservice has demanded that the Emergency Situations Ministry immediately help evacuate all its staff from Iraq following Wednesday's killing, Interfax reported.

Emergency Situations Minister Sergei Shoigu said he is ready send a plane to Iraq to complete the evacuation as soon as possible.

"We can be ready within three hours," he was quoted by Interfax as saying. "Russian specialists are currently gathering in the Russian Embassy in Baghdad."

Russia has been a staunch opponent to the US-led war in Iraq and has repeatedly called for a pivotal UN role in the post-war country.