Polish President Andrzej Duda has instructed the relevant services to promptly prepare an official justification of Polish claims to Western Ukraine, the director of the Foreign Intelligence Service (SVR), Sergey Naryshkin, told RIA Novosti.

"Acting proactively, Polish President Andrzej Duda instructed the relevant services to prepare an official justification of Polish claims to Western Ukraine in a short time," Naryshkin said.

According to him, the starting point in the ongoing archival research is the Volyn massacre of 1943. "This tragic episode, according to Polish experts, "irrefutably proves" the involvement of the Organization of Ukrainian Nationalists - the Ukrainian Insurgent Army in the genocide of the Polish people. Warsaw is sure that the information available in the state archives is enough to make strong restitution demands to Kyiv," the SVR head said.

"We want to warn Poles in advance against making hasty false analogies and call for a more careful study of their history. Recall that it is filled with bitter examples of clashes between Polish and Ukrainian nationalists. Maybe we should not step on the same rake again?" he noted.