Europe is scrambling to offer backing to Kyiv after US President Donald Trump blindsided allies by launching peace efforts with Russia over the Kremlin's three-year war.

Key leaders from the continent were to gather in Paris on Monday to discuss how to shore up any deal that Trump strikes and try to strengthen Ukraine's hand.

The proposal circulated by the EU's diplomatic arm said it "aims to accelerate and focus the efforts of the EU and member states to meet Ukraine's most pressing short-term needs".

It called on EU states to commit to delivering a specific amount of weaponry "as soon as possible in 2025" -- but did not lay out a figure.

The initiative covered "large-calibre artillery ammunition, with a minimum objective of 1.5 million rounds" as well as "air defence systems, missiles (deep precision strikes), drones."

It said each EU state would be assigned a financial quota to fulfil that would be worked out in relation to their gross national income.

Diplomats said the proposal would be discussed by representatives from the EU's member states in Brussels on Tuesday.

"I understand it is far from being close to an agreement," said one EU diplomat, adding that several countries had major questions on the initiative.

Another diplomat said the proposal was still "very vague", and it did not contain recommendations of how to avoid long-standing blockages from Hungary.

Brussels is keen to send a strong message of support to Kyiv as EU chief Ursula von der Leyen and her top team are set to visit Ukraine next week for the third anniversary of Moscow's invasion.

As Trump presses for a quick end to the conflict, Washington has said it now expects Europe to provide the "overwhelming share" of aid to Ukraine.