He has not publicly proposed a figure before but NATO officials previously floated a sum of 100 billion euros over five years, or 20 billion euros annually.

With uncertainty over future US support for Ukraine lingering due to the possible return of Donald Trump to the White House, foreign ministers will on Friday discuss ways to put military aid for Ukraine on a more solid long-term footing.

The talks will focus on hammering out the details of a Ukraine support package, meant to be agreed at NATO's Washington summit in July, that will also include changes to the way weapons and ammunitions supplies are organized.