French President Emmanuel Macron said it "would probably take several decades" before Ukraine could join the European Union in a speech to the European Parliament on Monday.
Macron said the bloc's current entry rules could see the process for Ukraine last several years, or "in truth" several decades, in a speech calling for changes to the structure of the EU.
The French president was addressing EU legislators about Ukraine's membership hopes at a ceremony to mark the end of a major year-long citizens' forum on the future of the EU, the so-called Conference on the Future of Europe.
Macron called on the EU to find "new space for political cooperation" in security, energy and transport with non-EU members, using Ukraine's entry bid as an example, in a proposal to loosen up the EU's rules for participation in the bloc.
Ahead of Macron's speech in Strasbourg, European Commission President Ursula von der Leyen said Ukraine is to get a first answer in June about its application to join the bloc, after a video call with Ukrainian President Volodymyr Zelensky.
Zelensky applied for entry in light of the Russian invasion of his country.
The 27 EU member states tasked the commission with reviewing the viability of the application soon after, an important but very early step in the long and complicated entry process.
The application or questionnaire serves as the basis for accession talks. There is no guarantee negotiations for entry could begin as unanimity among the member states is required to start the process.
The EU's formal membership candidates are Albania, North Macedonia, Serbia, Montenegro and Turkey. However, entry talks have stalled or dragged on for years.
Moldova, just like Georgia, applied for a EU membership after Russia invaded Ukraine. Both countries received their questionnaires to join the bloc in April.