EU internal market commissioner Thierry Breton said the priority was to ensure that most shells produced by European firms would go to Ukraine, which has been battling a Russian invasion for nearly two years.

"We are at a crucial moment for our collective security in Europe, and in the war of aggression run by Russia in Ukraine, Europe must and will continue to support Ukraine with all its means," Breton told reporters during a visit to Tallinn.

Speaking alongside Estonian Prime Minister Kaja Kallas, Breton also said the EU would reach by March or April its target of having production capacity for one million ammunition shells each year.

"We will continue to enhance our production capacity, probably around 1.3 to 1.4 million... at the end of this year and continue to increase significantly next year," he added.

He refused to reveal current production figures, saying they were confidential.

"With this capacity to produce one million shells... we need to make sure that most of this is coming to Ukraine in priority. Because this is where there is an urgent need," he said.

Kallas noted a recent claim by South Korea that Pyongyang had provided more than one million artillery rounds to Moscow in exchange for advice on military satellite technology.

"If North Korea can do it, Europe can definitely do it," she said, adding that "Ukraine is counting on us and we should not let them down".

"Russia is a direct threat to NATO's security... We all have to do more because the threat is real," she said.