Hungary will block a proposal to start talks on European Union membership for Ukraine at a summit of the bloc’s leaders this week, Prime Minister Viktor Orbán said Wednesday, adding that admitting the war-ravaged country would have unforeseeable consequences for the EU.

EU leaders are expected to vote on whether to begin membership talks for Ukraine during a summit in Brussels that begins Thursday. Orbán has maintained that he will block the proposal, which requires a unanimous decision by the leaders of all the bloc’s 27 countries.

Speaking to lawmakers in Hungary’s parliament Wednesday, Orbán said that the time for bringing Ukraine into the EU had “not yet come,” and that the development of a strategic partnership with Kyiv should be a prerequisite for beginning membership talks.

“We are interested in a peaceful and prosperous Ukraine, but this requires the establishment of peace as quickly as possible, and a deliberate deepening of the strategic partnership,” Orbán said, adding that such a process could take “a number of years.”