Hungarian Prime Minister Viktor Orban has "no reason" to block Kyiv from joining the European Union, Ukrainian President Volodymyr Zelensky said Wednesday on the eve of an EU summit.

"I asked him to tell me one reason why. Not three, not five, not 10. Tell me one reason," Zelensky said of his talks with Orban.

"I'm waiting for (an) answer," he told reporters in Oslo where he met with five Nordic leaders.

EU leaders will be in Brussels from Thursday to discuss renewing their support for Ukraine, with a macroeconomic package of EUR 50 billion and a promise of formal membership talks on the table.

Orban has threatened to veto both measures, which would condemn the summit to failure and leave Ukraine -- and its neighbor Moldova, also hoping for membership talks -- out in the cold almost two years after Russia launched an all-out invasion of Kyiv's territory.

Hungary insists it has principled objections to Kyiv's move for membership, arguing that Zelensky's wartime administration has not done enough to fight corruption.

Orban Wednesday reiterated his opposition to opening EU membership talks with Ukraine, calling it a "terrible mistake".

Zelensky said meanwhile he hoped to have "a very constructive meeting" with Orban "because we have common borders."