Kyiv has relied on Soviet-era stocks and Western deliveries for much of its defence against Russia's invasion, while developing its own weapons production.

"At this point the limit is not in production capabilities, it's all in the funding," Oleksandr Kamyshin, advisor to the President for Strategic Affairs, said at a conference in Kyiv.

"Each production facility tells us: I can do more, all I need is proper funding," he said.

He specified to AFP that Ukraine had a production capacity equal to $20 billion but could only manage to fund $7 billion with its own budget.

"It's hard to produce with money; it is impossible without money, that's why we encourage investment in the defence and security sector," Defence Minister Rustem Umerov said on the same panel.

One of the solutions, former US General David Petraeus suggested, would be to use some of the $300 billion in frozen Russian assets.

Ukraine's defence industry has recently made strides including the first successful test of a domestically-produced ballistic missile and the deployment of a Ukrainian-made long-range "rocket drone" called Palianytsia.