By Jan Strupczewski, Krisztina Than and Ingrid Melander

BRUSSELS (Reuters) - European Union leaders expressed confidence on Friday that they would clear a large package of aid for Ukraine early in 2024, despite a veto by Hungarian Prime Minister Viktor Orban.

All 27 EU states except Hungary agreed on Thursday to start accession talks with Ukraine despite its invasion by Russia, bypassing Orban's grievances by getting him to leave the room.

But they could not overcome his resistance to revamping the EU budget to channel 50 billion euros ($55 billion) to Kyiv and provide more cash for other tasks such as managing migration.

Kyiv is reliant on foreign assistance as Russia's war in Ukraine rages on, and U.S. President Joe Biden has so far been unable to get a $60 billion package for Kyiv through Congress.

EU leaders, who would prefer a deal backed by all members but also have a plan B, are expected to revisit the issue at an emergency summit at the end of January or early in February.

"We are working very hard to have an agreement by 27 member states," European Commission President Ursula von der Leyen said, adding: "But I think it is now also necessary to work on potential alternatives to have an operational solution in case that an agreement by 27, so unanimity, is not possible."

German Chancellor Olaf Scholz and French President Emmanuel Macron were among those expressing optimism on getting the aid to Kyiv, which is part of a broader multi-year EU budget plan.

"We have other ways of helping Ukraine, but we have not given up on the goal of finding a solution here," said Scholz, who diplomats and officials said played a big role in getting Orban to leave the room to clear the way for a decision on starting accession talks.

Macron said the EU was "not blocked" from providing aid next year, adding he felt Orban had an incentive to reach a deal.

The EU could continue to help with a workaround that involved a deal between 26 members and Ukraine, which would also deny Budapest access to linked EU funds, such as on migration.

The Kremlin praised Orban, who maintains close ties to Russia, and said the EU decision to open accession talks with Kyiv was politicised and could destabilise the bloc.

Orban, who has a history of trying to use disagreements with other EU leaders for his electoral benefit, told state radio he had blocked the aid to ensure Budapest gets EU money that is frozen over concerns about the rule of law in Hungary.

"It is a great opportunity for Hungary to make it clear that it must get what it is entitled to," he said.

The EU restored Hungary's access to 10.2 billion euros of frozen funds this week, but 21.1 billion euros remain locked.

'BAD DECISION'

Ukrainian President Volodymyr Zelenskiy hailed the approval of membership talks as a victory for Ukraine and Europe.

And while Lithuanian President Gitanas Nauseda said that while it made him "proud to be European", he added it was "only the first page of a very long, long process".

Orban, meanwhile, called the move a "bad decision".

"We can halt this process later on, and if needed we will pull the brakes," he said.

EU leaders ended talks on the financial package in the early hours of Friday, with all except Orban agreeing to provide Ukraine with 50 billion euros over four years. His veto blocked the funds, however, because the decision requires unanimity.

The best legal form for providing aid outside the EU budget is to be determined, but the Commission could coordinate a collection of grants for Kyiv.

Ukraine is unlikely to join the EU for many years, but the decision on talks took it a step closer to its long-term goal of anchoring itself in the West and leaving Russia's orbit.

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