She was in Kyiv on Europe Day to meet Ukrainian President Volodymyr Zelensky, who praised the European efforts but said Russia had used delays to gain momentum on the battlefield.

"We are painfully aware that Ukraine urgently needs more equipment and air-defence systems to defend itself against the aggressor," Metsola said.

Ukrainian officials and soldiers have repeatedly warned they lack ammunition to defend themselves against sustained Russian assaults as the war stretches into its third year.

"We Europeans need to deliver, we need to take responsibility, we need to intensify our support," she said.

On Wednesday, EU members states agreed to use billions of euros in profits from frozen Russian central bank assets to arm Ukraine and fund its post-war reconstruction, which Kyiv had been pushing for.

The EU had also promised to provide Ukraine with one million shells by March 2024, but fell short of that target.

"There were supplies -- and once again, thank God and thank you -- but not in the amount that was voted," Zelensky said.

Ukrainian troops would be able to stop Russia's initiative in the east as soon as the aid arrived, he said, while warning that Russia was "taking advantage" of any delay.

He also praised the increase in Ukraine's domestic production of weapons.

Zelensky and Metsola held the news conference in Kyiv as Russia celebrated its annual Victory Day marking the Soviet Union's defeat of Nazi Germany in World War II.

At the end of the conference, air raid sirens sounded.

"This is (Russia's) real attitude to peace. Their real attitude to the fight against Nazism," Zelensky said.