“The work is being carried out in a secret place,” RIA Novosti quoted Gavrilov as saying.
He added that the plane is 30% ready.
Earlier, the Russian Defense Ministry said that the Russian air defense system shot down a Ukrainian Mi-8 helicopter in the Donetsk People's Republic and destroyed nine unmanned aerial vehicles in a day.
Before that, a Ukrainian Mi-8 helicopter was shot down by Russian Aerospace Forces in the area of Novotroitsky, Zaporozhye region.