DUSHANBE, August 4, 2014, Asia-Plus -- Russia is conducting military exercises with more than 100 aircraft in the country''s central and western districts near the border with Ukraine.

Russian news agency Interfax quoted a Russian air force spokesman, Igor Klimov, as saying that aircraft including MiG-31 fighter jets and Russia''s newest frontline bomber, the Su-34, would be used in the exercises and that the aircraft would conduct missile practice.

The exercises were planned to take place from Monday to Thursday.

Western media sources note that the exercises came as fighting continued in eastern Ukraine as the advancing national army tried to seize control of the rebel stronghold of Donetsk.

A spokesman for the Ukrainian military operation, Alexei Dmitrashkovsky, said government soldiers were fighting on Sunday to hold positions they had taken on the edge of Donetsk, but were meeting resistance.

The separatists, who are in danger of being encircled, have renewed their calls for Russia to send troops to their aid, Reuters reports.

Ukraine and western leaders reportedly say they have evidence that Russia is arming the separatists. Russia denies this and describes the Russian citizens fighting in eastern Ukraine as volunteers.

The ongoing battles have delayed the start of an international search for body parts still lying in the fields where Malaysia Airlines flight MH17 was shot down on 17 July, killing all 298 people on board.