The European Union signalled its long-term support for Ukraine on Monday as its foreign ministers convened in Kyiv for a historic first gathering beyond the bloc's borders.

The meeting came as disagreements grow among EU members over support for Ukraine and as Kyiv's forces make limited gains in a high-stakes counter-offensive against Russian troops in the south and east of the country.

"We are convening in a historic meeting of the EU foreign ministers here in Ukraine, candidate country and future member of the EU," the bloc's foreign policy chief Josep Borrell said in a statement.

The purpose of the meeting was to "express our solidarity and support to the Ukrainian people," he said, acknowledging that the gathering "does not have the aim of reaching concrete conclusions and decisions."

President Volodymyr Zelenskyy told the ministers that the length of the war, now in its twentieth month, will depend entirely on support Ukraine receives from its allies.

"Our victory directly depends on our cooperation: the more strong and principled steps we take together, the sooner this war will end," Zelenskyy said in a statement.

To bring about a speedy end to fighting, he urged the EU to expand its sanctions regime on Russia and Iran, which has supplied attack drones for Russian forces.

And he also called for the "acceleration" of work by the bloc to direct "frozen Russian assets to finance the restoration of war-torn Ukraine."

The EU's 27 nations have remained broadly united through the war on their support for Ukraine, hitting Russia with 11 rounds of sanctions and spending billions of euros on arms for Kyiv. (AFP)