MOSCOW, Aug. 4  -- Russia on Monday started a week-long military drill involving bombers and fighter jets with the purpose of improving coordination between its aviation and air defense systems.

"The training will involve over 100 aircraft of various branches of aviation such as the destroyers Su-27, MiG-31, multi-function complexes Su-34, frontline bombers Su-24, helicopters Mi-8, Mi-24, and Mi 28N," a Russian air force spokesman, Igor Klimov, told reporters.

He added that the training was conducted "for the first time on the territory of three military districts," namely the western, central and southern military districts.

The combat jets will test weapons "on land and air targets on new ranges, and will be conducting real and electronic launches of anti-aircraft missiles in Ashuluk, (Southern) Astrakhan region, which is intended to aid the coordination between aviation and air defense systems," Itar-Tass news agency quoted him as saying.

The spokesman also said Il-78 air tankers will conduct in-flight refueling of MiG-31 destroyers and Su-34 bombers behind the polar circle.

"The time in flight will double and will reach some eight hours," he said.

As clashes kept raging in eastern Ukraine, Russia has been trading blames with major Western powers over issues concerning the beefing up of its military presence near its borders with Ukraine.