The European Union has criticized Russia's move to fast-track citizenship applications from people living in conflict areas in eastern Ukraine, calling it "another attack on Ukraine's sovereignty by Russia."

Russian President Vladimir Putin signed a decree Wednesday to expedite the applications from some Ukrainians living in areas held by Russia-backed separatists. Those granted Russian citizenship would have to swear allegiance to Russia.

European Commission spokeswoman Maja Kocijancic said Thursday the fact that Putin's move came just days after presidential elections in Ukraine "shows Russia's intention to further destabilize Ukraine and to exacerbate the conflict."

Volodymyr Zelenskiy, who won a landslide victory in Ukrainian presidential elections Sunday, said Russia's move confirms its role as an "aggressor state" in the conflict in the east.