Ukrainian President Petro Poroshenko has called his successor Volodymyr Zelensky and congratulated him on his victory in the election; they agreed to meet soon and discuss the policy on the Russian track.

"Now we must show all our partners a unified Ukrainian stance while the Kremlin is conducting the next stage of the hybrid war against Ukraine by means of the issuance of Russian passports in the occupied territories. This way Putin is preparing the grounds for the new round of military aggression under the pretext of allegedly protecting Russian citizens' rights," Poroshenko said in a statement posted on his Facebook page on Tuesday evening.

"The Russian Federation deserves considerable tightening of the sanctions against it," Poroshenko said.

"This issue will be the main thing I will dedicate the last week of my presidency to. But continuing and concluding to resolve this issue is already an area of the new president's responsibility. Therefore, I believe, we should coordinate our efforts," Poroshenko said.

During the telephone call, the parties agreed to meet in the near future, he said.

"The electoral competition is in the past now. We must not give any chance to Putin to use the transitional period in Ukraine and our democratic process of the handover of the authority. I expect that the president-elect will support this stance too," Poroshenko said.