Russia's defence ministry said on Thursday it had taken out military infrastructure at Ukraine's air bases and "suppressed" its air defences, Russian news agencies reported.
The ministry denied reports that its aircraft had been downed over Ukraine.
Earlier, Ukraine's military had said five Russian planes and one helicopter were shot down over its Luhansk region.
"The air defence assets of the Ukrainian armed forces have been suppressed," Interfax news agency quoted the ministry as saying.
"The military infrastructure of the Ukrainian Armed Forces' air bases has been taken out of action.
"Information in foreign media about a Russian plane allegedly being shot down is not true."
Rescuers search for 140 people after Indonesia ferry hits bad weather
Saudi Arabia shuts key oil pipeline after drone attack
BRICS members agree joint declaration at New Delhi summit
Death toll in Philippine ferry fire rises to 76 as rescuers recover more remains
Russian attacks kill six, injure dozens in Ukraine, Moscow says it hits ships, plants
