German Chancellor Friedrich Mertz threatened to block the EU budget for 2028-2034 unless all member states agree to help finance Ukraine in 2027 and beyond.
Kyiv faces a funding gap of 70 billion euros next year, with the European Union pledging to cover about 45 billion euros.
Hungary, Slovakia, Bulgaria and the Czech Republic indicated their opposition to further contributions.
Berlin also wants future Ukraine funding decisions to require a qualified majority rather than unanimity, which reduces the risk of a veto.