German Chancellor Friedrich Merz's groundbreaking plan to grant Ukraine "associate membership" in the European Union has received mixed reviews in Brussels, with questions raised about its legality, feasibility and political implications.

In a letter to his fellow leaders, seen by Euronews, Merz proposes a tailor-made status that would give Ukraine access to decision-making bodies without voting rights or portfolio and to certain EU-funded programmes on a "step-by-step" basis.

He also envisions Kyiv able to request assistance from other member states in the event of armed aggression through Article 42.7 of the EU treaties. This, he argues, would create a "substantial security guarantee" to deter Russia.

"It is now time to boldly move on with Ukraine's EU integration through innovative solutions as immediate steps forward," Merz tells his peers.

In Brussels, Merz's letter drew attention and raised eyebrows amid ongoing efforts to lift Hungary's veto on Ukraine's accession by the time the 27 leaders meet in June.