Distributing Russian citizenship to the inhabitants of Donbas is a violation of the international law and such citizenship won't be recognised by the international community, as it was prior the case with the inhabitants of Georgia to whom Russia started "passportisation", or Crimea.
The EU condemns "passportisation" and estimates it as a step which aims to destabilise Ukraine further, as it was stated by the Spokesperson of the EU External Action: "The signature by President Putin of a decree entitling, inter alia, people who permanently reside in certain areas of Ukraine's Donetsk and Luhansk regions to apply for Russian citizenship in a simplified manner, is another attack on Ukraine's sovereignty by Russia. The timing of such a decision immediately after Ukraine’s Presidential election, which demonstrated Ukraine's strong attachment to democracy and the rule of law, shows Russia’s intention to further destabilise Ukraine and to exacerbate the conflict. We expect Russia to refrain from actions that are against the Minsk agreements and impede the full reintegration of the non-Government controlled areas into Ukraine". Reed full statement here.